I felt that the Ergo was too short in the body, and didn't like the internal harness of the Beco, so I looked elsewhere. I ended up with an Olives and Applesauce which I love to bits.
I know I've talked about it on here before, but - I can wear my 31lb 22mo for hours at a time, and I've even worn my then-40lb 3.5yo for an hour or so. That wasn't the most comfortable thing ever, but I also wasn't in excruciating pain, and it was at the end of a long, exhausting day.
The little guy, I wore over the summer (I think he was 24-28lbs then, 18-20mos) sometimes all day long. We do a lot of travel and field trips, and some of them are not suitable for toddler feet. The only problems I've had were when it's HOT out, when I become a BWing wimp and figure out a way to mash a stroller into my overpacked vehicle, lol. Also, I cannot pull up the sleep hood on my own -- one of the big kids or a passerby has to help me. For a 7m old, he would probably still sit down in the body enough that it wouldn't be an issue yet.
Anyways, it does an awesome job putting his weight onto my hips/legs, and if I feel him in my shoulders I know I've tied it incorrectly. I got mine used off of FSOT at TBW, think it was around $80.