For me personally, I'd rather not use the erasable pens. I took the Princeton practice test, and they told us to use pencils, and everytime I ran into a snag in my writing, I would erase rather than cross out because hey, it's a reflex. Depending how big of a boo-boo you've made (and I tend to make doosies), you could spend a lot more time erasing than crossing out. So I don't give myself the luxury; I just use regular pens.
I've read on here where people liked using the erasable pens. It's just personal preference. Whatever you cross out, they do not count into your writing (if they did, what they read probably wouldn't make much sense).
I don't know what the rule is, but I wouldn't use the erasable pen. It takes longer to erase a screwed up sentence than a crossed out one, and it doesn't look that much neater to erase it...
I think erasable pens are a great idea. I've been using them for the past few practice tests that I have taken. They are great if you have to go back and revise a sentence that you have already "surrounded" by another sentence.
It's personal preference, I guess, but my vote is for erasable pens.
RE: Pencils -- I didn't think that you were allowed to use pencil on the WS sesction (MCAT instructions say to bring pens for the WS section.) If so, I would just use pencil.
RE: Pencils -- I didn't think that you were allowed to use pencil on the WS sesction (MCAT instructions say to bring pens for the WS section.) If so, I would just use pencil.