I started this game with hopes of being an awesome Summoner only to be sorely disappointed that the pet is a glorified auto-turret and the majority of the job's damage came from DoTs, which (to add insult to injury) the summon BUFFED for you (via the old Contagion extending all dots by 15 seconds). This to me is not what a Summoner is, I envision a Summoner much like Aeons from FFX where the summon does the majority of the damage and the caster buffs it and debuffs the boss and has some kind of filler like ruin, but not strong dots. Obviously Demi-Bahamut is a step in the right direction towards this, but Ruin III and DoTs are still a significant portion of the class's damage, not to mention skills are gated behind the dots (Fester and by extension DWT).

All this being said, the mechanics of the job aside, it is insanely powerful. RDM is much more straightforward, streamlined, and intuitive, but far less powerful. You should absolutely play the job that you want, as both have their merits for different gameplay styles/situations.