The thing about corrosion, and Martyr Wraps especially, is that it's not too bad in small ammounts but really silly in large ammounts.
It's the whole Dragonshield / MW question - I'll always beeline for those two because they're just plain better than the CO +8 charm or the Sticky Stick. I must've run into the stick a dozen times but I've never actually picked it up because I had MW prepped for the vast majority of my last profile playthrogh.
Sticky stick and MW don't stack (as far as I know), and MW is a superior item if you prep it, so the stick gets the short end of a lame pun. Same thing with the CO charm - neither it or the Dragonshield turns up in shops, so if you can only prep one, the only reason not to prep the dragonshield is because the other is a small item. Same with the Stick and MW - this does save you a compression, but it just doesn't seem worth it (even though I might be a narrow minded git).