I bought an Ergo carrier with infant insert for my 2nd baby so I could do stuff with my toddler while carrying baby. You CAN bf with the Ergo but it's not perfect unless you're one of those very coordinated people who can loosen and tighten straps on your back with no problem. I am not, haha. So I leave the straps alone and try to lift my boob up to my baby when he fusses in the carrier. It DOES work but if he's really hungry then I'll take it off for a longer feed as I'm not convinced he can suckle the same way in the carrier as out of it.
There is a YouTube video that shows you how to loosen one strap to bring baby down to the level of your boob. I cannot do it.
I have worn him in the Ergo for long stretches of time, though, and he seems to like it most of the time. It is VERY comfortable to wear, which is what I love. A bit tricky to put on but you get used to it.