A couple of things I'd like to note

[Estellios]

I remember when that was a selling point of the game (back in 1.0). "Oh, your armor breaks while out fighting? Change to a DoH, or have a party member change to DoH, and let them fix your gear."

Do people use DoHs to fix gear in 2.0? Seems like the NPCs can repair everything to max. Any reason or benefit to use DoH repairs?

You save some money if you repair it yourself. Dark matter can be bought for company seals or just cheaper-priced than NPC repairs.

[BlueMage]

You save some money if you repair it yourself. Dark matter can be bought for company seals or just cheaper-priced than NPC repairs.

I'm guessing 1 dark matter per piece of gear? And if I'm not a crafter, can I have a crafter friend repair my gear for me still?

[Estellios]

I'm guessing 1 dark matter per piece of gear? And if I'm not a crafter, can I have a crafter friend repair my gear for me still?

Yes it is 1 dark matter per piece of gear, but what level of dark matter depends on the gear level. It says on the item description which dark matter you need.

Also, I'm not sure if we can repair other players' gear anymore. I tried looking for the function and it may be gone, possibly to make crafting more appealing. It is possible that I missed it or it's disabled or unlocked, though.