awesome dude!
glad you bought a bike and are getting back into it- what did you end up getting?
i went w spd's cause thats what your 'supposed to do' i'd bet at least 90% of people you see who dont strictly DH use clipless. 100% of my friends who ride ride clipless.
i found after several bad wipeouts that they made me a very hesitant rider. i would dismount and walk over technical shit that i would normally eat on flats to save myself injury. i found i wasnt going into corners and getting up and over top of the bike to push it down when i was clipped in, i was slowing down more and sitting back in corners which causes the bike to slide out a good deal of the time if your being aggressive. it just sucked all the way around. and i gave them an honest try. 3 weeks worth of rides and i prolly was averaging 100k a week at the time. ya id have no problem saying i put prolly 250km on my spds.
it was ruining the enjoyment of my riding cause it was taking away all the things that made me a good rider- flowy and fast in corners, and aggressive over technical shit.
on flats i have way better control of my bike. im not afraid to attack something that might throw me. im waaaay more aggressive on flats.
i think it depends on the type of trails you ride. up here theres a lot of rock and root. very very technical shit- google 'buckwallow' theres youtube vids of the trails too.
the comfort of being able to attack a corner and just put a foot out, or put a foot down going over gnar is a huge upside for me and makes me faster in the long run cause my aggression increases exponentially.
if i were riding mostly rollercoastery flowy shit id stay clipless. i noticed a huge increase in the torque i could generate w them, and i liked the secure feeling of being strapped to the bike. but i find being strapped to the bike cause me to not focus on feeling what its doing like i do on flats a pair of 5tens cause you really become one w it.
everyone i ride with is clipless. im the only guy who isnt. im not getting left behind. in fact the only guys i lose pace w are cardio monsters on bigger switch back type of ascents. but technical riding and flowy shit, forget it- im as fast if not faster than a lot of guys i ride with.
for me the upside to flats far outweighs the upside to clipless.
* edit- trust me you'll get a lot of 'whos the new guy' look everywhere you ride on flats. i think peer pressure cause most people to switch over