Bonus Whores Grades (NL/PL 6 Max)

[spkid]

IMO, BH is a good site for keeping up to date on new sites, deposit bonuses and reload bonuses. I was wondering what people think about their grading of some of the more popular U.S. friendly sites. Here are some grades they have given for NL/PL 6 Max (easiest to beat would get an "A"):

Pokerstars D+
Full Tilt C-
BoDog C-
Prima C
Cake C-

A couple others:

Carbon C
Pacific B

I haven't yet tried FT since I started playing NL (4 months ago) but I have tried PS and found the games tougher than at UB and Cake.

When limit poker was what everyone played it seemed liker the larger sites like Party Poker had the best games. Now, the largest site, PS, has the worst grade from BH. Any ideas as to why this may be? I've heard that the reward program there is good but that most players would prefer rakeback.