The tier list is primarily concerned with levels 6-15. I think there was also a project attempting to do separate tier rankings for different level chunks and degrees of optimization a while back that might be worth looking at.
The one thing about the tier list I'd change is that I'd break what is currently High T4/Low T3 area into a separate tier and maybe expand what's left of T3 upwards a bit to cover some of what is now considered low T2 (online vestige Binders, Arcane Disciple Dread Necros/Beguilers, and the like). The reason that the Warlock/Warblade/Swordsage/etc argument keeps coming up is that the line between T3 and T4 as it stands is in such a murky grey area. Moreover, the High T3 types, like Factotums, Bards, Dread Necromancers, and yes, Binders are operating on a pretty clearly distinct level of ability (not bad enough that the classes can't play together, but one tier of difference is supposed to be manageable). Of course, that might just create new grey areas, but I think it'd turn out cleaner overall.