Good that's what I thought. When my blood elf twins are 80 (prot pally, holy priest), I'm planning to RAF boost 4 additional 60's and would do this:

Main acct (A) hosts the prot pally
2nd account (B) will RAF in a 3rd account (C)
Create lowbies on (B) and (C)
(A) (B) and (C) form a party, the link between (B) and (C) will be active

So even though (A) is clearing the instance and doing all the killing as a level 80, (B) and (C) still earn triple XP because they're linked and the same level, amiright? I know they'll take a hit off the base XP because an 80 did the killing, but then they should have the triple XP bonus granted to the reduced XP hopefully still making it higher XP than normal, or at least normal XP but coming in alot faster because I'm clearing the instance in minutes instead of an hour...