I'd like to see those deal with 85-90w on the upstroke alone.... that 2.1N force back & upwards at 70 rpm
Wow, somebody not had a compliment about his incredible power today then?
On the OP and the responses:-
clipless moments/falling over - never has so much total crud been talked about something, all this hilarious, not a problem, laugh it off - it's purely personal anecdote at best - question a bit more closely and some might even admit that yes they were hurt but not badly - now go and tell those that have been seriously injured in 'clipless moments' that it's just a laugh and the advantages were worth it. I AM NOT saying don't go clipless but I am saying don't believe everything you hear.
feet slipping on pedals, sore feet, etc, etc - not for me, get flat pedals that give a decent supportive platform/grip and you can ride in anything - though I will admit to not doing too well in flip flops last year, but then I don't do too well walking in flip flops.
power - climbs and sprints, yep I can see that - everything else...nah....you'll hear plenty claim that it's night and day but you won't see much in the way of - 10 miles takes me 40 minutes on flat pedals but only 20 minutes with clipless - in fact the differences, if any, are more likley to be measured in seconds than minutes. As for pulling up on the pedals, that only happens on limited occasions.
pedalling properly/knee pain - more crud, you can pedal perfectly adequately without being attached to the pedal and you can reposition your feet to suit how you are at that time and on that day. Search the forums and you'll find plenty about knee pain, a lot of which can be resolved by getting the saddle/pedal relationship correct. After that though it becomes a list of how are your cleats? how much float? have they been fitted properly? try moving them a few mm at a time, get a proper shoe fit with special wedges, try a different pedal/shoe setup. It's a marketing wet dream, not only have they created an entire shoe/pedal industry but they've got people spending more dosh to try and tweak to get the perfect fit.
As per Rivbikes:-
http://www.rivbike.com/article/clothing/the_shoes_ruse
Go clipless, don't go clipless, I don't care, but don't accept at face value the garbage that's trotted out on the subject. Have a think about reality and what you want to do, if that involves making a living in cycling then clipless is your friend, anything else is just slurping the marketing coolade.