As I look through Centauri Knights and Trigun D20 (expect reviews soon!), the words of my original review come back.
"My worry extends to future products from GOO. After all, Mecha d20 isn't being touted as being fully compatible with D&D, it's noted as being fully compatible with BESM d20. Does that mean that materials like A Game of Thrones or Slayers are using BESM too? With each release I can see BESM becoming more and more enriched and useful but also see those books lacking the compatibility that 95% of the standard d20 books have with the core rules. "
This to me puts BESM d20 in a simliar category as say, d20 Modern. Simliar engine, but different, sometimes vastly, results. Still love it though and looking forward to the new version with the d20 Mecha rules incorporated into 'em.