Hiya.

C4 requires a very solid understanding of C++. If you have that, then C4 might be the way to go as it lets you write what you need it to do. The tools for C4 are still new (as is the engine itself), but you get full source to the engine and the included tools. It can also be compiled to run on Mac computers.

Eric (the creator of C4) is a *great* guy, and uber-smart. You can't go wrong with a guy like that at the head. Also, with C4, if you add more to the team later, you only have to buy licenses for the programmers...all your artists can use the tools to import/create the assets for free. So, if your team consists of 6 guys, 2 of which are programmers, you only need to buy 2 licenses...not 6.

C4 is also "cutting edge" compared to A6. The potential for C4 is a LOT more, IMHSHO, than it is for A6. Maybe when A7 gets out it will be different, but compared to A6, C4 is leaps and bounds ahead in capability when a serious team and decent programmers/artists are behind them.