Trial accounts, Vanilla accounts, Wrath accounts (oh my!)

So I'm currently 3-boxing Wrath accounts, and I'm planning to open up 2 trial accounts for RAF bonuses. I may upgrade to Vanilla (or Battlechest) accounts after the 10 days, and who knows I may go completely nuts, upgrade to Wrath, and 5-box.



My question is on the install folders I will run the accounts from. I know I had trouble before trying to run an account that was licensed for Wrath on an installation that did not have Wrath, but will I run into the same problem with a Trial, Vanilla, or Battlechest account in that it will refuse to run on an install with Wrath applied?

all wow accounts are forward compatible and so will work with the wotlk and all future expansion packs. although you obviously do not get access to the expansion pack's content
i personally am still running 2 vanilla accounts on my 5 team with the other 3 being wotlk.

The one thing I did notice is when I tried to move an undead lock from my wrath account to my vanilla wow account. It told me I needed a wrath account at the destination account which is curious because he's an undead lock lvl50 and hasn't even been to any BC content. I wanted to move a belf hunter and also make another DK so I upgraded anyway just sooner than I expected.