At first I thought you were talking about going new... I am a fan of the FK04. However, if all that is on the market at the time is the 05, I'd say do that. I have been told by people (national caliber drivers) that have kept up with the latest cars that X-ray and Corally have to offer, and that the 04 was still their favorite. The only thing that I fear with a chassis this old (?) is parts availability down the road.