We are about to start on our next game and I am thinking of using A6/3dgamestudio as the game authoring tool. Are there any major pitfalls, especially regarding tabbing in and out of the game. Any other pitfalls with regard to the performance, scripting, compatibilty etc.?

I'm not sure about pitfalls, but a friend of mine wrote an A.I. plugin for the GS game engine (available on GS site forums) and he wrote a demo in GS that ran fine on my machine, but thats all I know on the subject