Hmmm, does meldshaper level have the same other-levels-count-half thing that Initiator Level in ToB has? I don't think so -- I think I'm just mixing it up with the rules for meldshaper level for Shape Soulmeld. But hey, at least non-incarnum classes could qualify for this PrC at Level 12? ...
The obvious ones you're missing are (1) is 10 levels long, and (2) hasn't already been used in an Iron Chef round.
There's also a concern about making them classes that are more open to qualifying for in a variety of ways, although some previous rounds have basically ignored that guideline anyway.