For me it came down to price. I was already stretching my budget when I purchased the 7s. If I had a bigger budget but the same value conscience, I would have chosen the 8s mainly for the bigger battery (primarily), Deore 10-spd, and rigid fork. The 9s is a sweet bike, but I still think the 8s offers better value for the price (IMHO).
Interestingly the 7s (speed) has the same MT520 4-piston brakes as the 8s and 9.9s, and this was a selling point for me. I love the brakes! The 7 (standard 20mph non-speed version) has different brakes (MT200) than the 8 (as noted by @Stefan Mikes in post #4). Nothing wrong with the MT200 though... they'll stop you too.
Having owned the 7s for about a year, I have been pleasantly surprised by the Alivio 9-spd. It's been pretty rock solid for me and the gearing is perfect (for me). Nothing wrong with the fork on the 7s (other than being heavy), but I just like rigid forks especially when compared to lower-end suspension forks (I acknowledge that most people prefer suspension forks). I would definitely still like a 625 Wh battery.
Interestingly the 7s (speed) has the same MT520 4-piston brakes as the 8s and 9.9s, and this was a selling point for me. I love the brakes! The 7 (standard 20mph non-speed version) has different brakes (MT200) than the 8 (as noted by @Stefan Mikes in post #4). Nothing wrong with the MT200 though... they'll stop you too.
Having owned the 7s for about a year, I have been pleasantly surprised by the Alivio 9-spd. It's been pretty rock solid for me and the gearing is perfect (for me). Nothing wrong with the fork on the 7s (other than being heavy), but I just like rigid forks especially when compared to lower-end suspension forks (I acknowledge that most people prefer suspension forks). I would definitely still like a 625 Wh battery.