For me personally, the stopping/going thing isn't so much of the issue as stopping for extended periods of time to wander around on foot. But being as you said that you generally carry around a backpack, that wouldn't be an issue.

Having issues with stopping/going with clipless is not so much a prominent issue once you get used to the whole thing. Just be careful, really. And if you fall, no big deal, everyone does. The difference between clipless and just straps and clips is large, in a small way. You'd be surprised how much more up-pull you get, and how much it helps to have back-pull. The only reason I ride straps and clips majority of the time, is because my commute is too short to justify the clipless and extra luggage with shoes (my bag is on the smaller end). Being said, if you're mainly going a block or ten blocks, I would stick to clips and straps. If you're talking five to fifteen miles, I would consider it more thoroughly.

Just my $0.02

Oh, and I am using Egg-beaters (Quattro SL's to be specific) with a set of Nike shoes.