I vote for and LOVE my BECO butterfly 2!
My husband has the Ergo Sport and he absolutely loves it, me not so much. I'm very petite, only 5' and my husband is 6'1", so the Ergo wouldn't fit me properly around my waste or adjust to my torso. I searched like you, far and wide and researched like crazy with money as no issue to find the PERFECT carrier....and I did. The BECO adjusts to as little as a 23" waist and even has a removable infant insert. The BECO is a little bulkier than the Ergo because of the fabric, but it still folds/rolls up quite small. The straps are more padded than the Ergo too. Our 9 month old son is more comfortable with me in my BECO vs my husband's Ergo. (I got this when he was 5 months)
I feel like it hugs his body more securely plus I get tons of compliments whenever I wear it. Another one of my favorite things about the BECO design that's different from the Ergo is that you can pass your baby to your spouse, mother, or friend, and not have to take them out, and adjust again, etc. When you insert your baby they're in a separate "compartment" and not right against your body, so you can pass them over like a backpack. (I may not have explained that clearly, check for a video on you tube). It's been useful many times when I'm out shopping with my Mom and want to run into the fitting room real quick.
I think it's the way to go instead of a sling - especially with all those scary recalls. If you want sling advice (I know this is already long, sorry) I have a BALBOA and only use it when our son's asleep ...restaurants, relatives house, etc and this week I'm going to use it to cradle him on a red eye flight to Canada so I know he's secure in my arms and on my lap. I wasn't too comfortable using it for him when he was an infant, probably again because I'm so tiny, so I always ended up cradling him in my arms while wearing the sling - so much for hands free! They sell inexpensive slings with leg inserts (similar to your baby being strapped into a bouncer chair) which I thought was a brilliant idea and I wished I had that when he was younger. I've seen them at Target and Babies R Us.
Ergo is great too, my husband absolutely loves his...just curses the day I got mine since our son likes it better LOL
Hope that helps and congratulations on baby #2. My son was born in September, so I had to endure the hot California summer last year too :) Best of luck staying cool, and best wishes for a safe and happy delivery!