I'm currently playing SM on VC and wanted to do a 100% run and cannot find the last missing item. I have 230 Missiles, 50 Super Missiles and 45 Power Bombs. It looks like I'm missing a Power Bomb tank, right?
So whch are common ones that are often forgotten / missed?
2 in red Brinstar (the "first" PBs and the ones in the giant sidehopper room just above them) 1 in green Brinstar (in the room with the Etecoons) 1 in blue Brinstar (left of morph ball) 1 in pink Brinstar (in the room with the two giant sidehoppers just below the misiles you're "supposed" to have grapple for) 1 in Maridia (in the right sandfall from the big snail room) 1 in Crateria (in the room off of the landing site) 1 in upper Norfair (past Crocomire) 2 in lower Norfair (1 on the way to Ridley, other past the missiles to the right of the way back to upper Nrofair)
hahaha I could never tell you the location of your missing item. Every time I go for 100% I miss a different item each time. I've missed more than one, on occasion. Just like I had to replay Metroid Prime through like five times until I finally got 200%. >_< stupid collection.
Anyway, Does it really matter if you finish SM 100%? I mean, is anything different?
Not really. The tally at the end of the game is really only for your 'information' that you were able to find everything. I mean, you don't even get to use everything you find anyway (such as: how many powerbombs do you have left over when fighting MB? -A whole bunch). Even though having everything isn't a requirement to finish the game, sometimes it's just nice to know if in fact you were shooting for that 100%.
I almost always go for 100%. There were a couple times that I can remember I didn't get it. Once I forgot the X-Ray, and another was the Craterian/Crash site Acid room PowerBombs.
There is of course a trade-off. The fewer items you collect - the faster your time can be.