As someone who's been leveling Botanist as one of his mains, this isn't really something I'd want to see them have. I don't believe DOL/DOH should have any offensive/defensive abilities in the means of a pet. What they need to do is fix up the eluder abilities, as it stands now each gathering guild is in each region. As a guild they should have the proper knowledge to evade any foes that prove to be dangerous.
Since I do understand what you're trying to do to make DoL more dynamic, I think a simple enough start would be this.
Revamp Eluder abilities, for DoL Botanist/Miner/Fisherman they would get
Botanist=Elude in Grida Region
Miner=Elude in ulda region
Fisherman=Elude in LL region
The Eluders would range from I-VI and I believe it should go 1-15/16-30/31-45/46-50/51-65 since by the 40's we are dealing with mobs that range in the 50+ so it would only make sense to have access to Eluder VI in the 40's
As for eluders in the other 2 regions they should be GM that you can obtain in any of the three regions since logically they should all be investigating said areas.
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As for any role in battle they should only serve as a means to support, since they do all have a unique eluder they should excel in being able to exploit said mob types since they analyze those mobs. But for the most part while it wouldn't be a game breaker to have them as a support it would make the usable if you are in need of another ally.(Mainly for dungeons)
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Roles in dungeons:
Now the two dungeons we got are interesting but I don't think DoL/DoH should be left out. It's easy enough to include DoL into the concept they can have unique traits to find special areas within the dungeon to unlock secret areas
Fisherman=Water holes and such for secret areas
Miners=Sense walls for hidden passages
Botanist=Studies the wildlife within dungeons to see any little oddities within the vegetation
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As for DoH there is an easy way to include them, now it wouldn't be for every dungeons but I believe there should be "legendary workshops" where renown crafters crafted from. The dungeons that support this concept would have certain crafters that can gain something out of that dungeon. Basically how it would work is when you check a dungeon it would let you know what DoL/DoH can be used to find secret passages or obtain secret blueprints for special synths that can only be done if you have the KI.
However DoH could also unlock hidden areas through synthesizing the right materials. Which are mainly in the form of loot found within the dungeon or mysterious mobs that form around said passages that drops the items needed for the synth. The synth items in question would never serve any purpose outside the dungeon and would automatically be lost upon leaving the dungeon, but basically upon opening the passage you may find a secret chest or maybea hidden boss or perhaps. my final idea.
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When SE mentioned how mobs were going to drop RARE/EX items in XIV I feel that it was a bad move, there is a much better way to go about it. When I think of RARE/EX items in XIV I think of legendary items with hidden powers behind them. Basically another way to obtain skills and traits through absorbing your battle progress in the weapon and then drawing it out to gain said ability in which the weapon itself become a catalyst to customize if you liked the design. Like say you got a neat looking sword and you wanted to keep it after obtaining the ability. You could integrate the materia system in which a crafter can make the weapon as good or even better then other weapons of that rank.
But ya there are a lot of ways DoL/DoH can go, right now DoH does have materia going for it but DoL is seriously lacking something in the "be a class you can have a full experience" concept that they were going for.
While your idea is well though out just personally speaking it isn't something i'd want. I would rather have more focus on either being more accessible to be part of the dungeon experience or a support using my knowledge of the wildlife to help the fighters take down the foe. Kinda like how there are those stories where the ones with no battle experience are able to tell the ones that can fight an exploit they know of the beast they are taking down or perhaps they have an incantation that can weaken said foe to make it easier for them. That's the kind of gaming experience I would like for DoL.
but ya, on one last note another thing I was trying to contemplate is Botanist have gardens, Fishermen can have fish tanks? And I guess Miners could have refineries where they can alter the ore they obtain and change it into other ores if they have the right procedure, though it wouldn't always be successful and a tad risky, perhaps they could even create ores that can only be made in a refinery. A garden is easy enough, basically botanist would have a plot of land in which they can grow anything they can gather, this is FF so why be limited by seeds lol. For fishermen they could create exotic unique fish or perhaps the ability to obtain pearls and such through the proper breeding. As for miners they would be able to combine ores to create new ores and such.
For this I would say each one should have it's own level that can't go above the classes current rank. So baiscally as Botanist, you would switch to Focus "Gardener" in which you would obtain skill points while you garden, instead of it being based on RL I would moreso integrate a point system like those popular browser games where you have a certain amount of points and obtain a few every few hours like anime/guardian aspect.
Basically they would be given options to care for their creation and each material in question would take a certain amount of "time" to mature, Each move you do would use up points and spend a certain amount of time. Basically the idea I"m trying to convey is that it wouldn't discourage those that may not always have time to do it to lose out on their progress if they couldn't get online or fail because a VU/maintinence went on when they needed to be on. It's basically a concept so casuals can do it without being stressed but hardcore can also do as well, they'll just be able to be more on ball of their points and use them all up while casuals may reach their capped points saved up so they won't always use all their points.
But ya those are just all my random ideas for DoL/DoH sorry if I hijacked your thread a tad but though you might find some of these ideas interesting, while I'm sure a lot of them are scattered about if I only knew what SE had planned for these disciplines it would be a lot easier to give them ideas or at least understand what they are going for lol.