
there are limits, but you can overcome them. For the usual indy game, even if cmercial and it's quality, the main difference is speed. When you have it all in an uber powerul package like Max, you go quicker. Except in some areas. There are better poly modelers out there imho than max tools for this, in my very personal point of view. Just faster, and more flexible (Silo, Wings3d, Zbrush, etc.) In the free and cheapo worlds.
collada is also supported well by XSI.
Ok, I think x format + MIM or any of the other level formats that been done for irrlicht are more than enough. Of course, if you count on a format able to port lights, camera and its animation (of both lights and cameras) and even shaders, direct from your Max, XSI or whatever, heck, you'r close to paradise. But I've only used that in ingame tools done by the game coders of the company, very rarely in a free or midcost game making tools or engine. And..the attempts to make these tools in midcost tools...are often not very good; you never get the power of Maya , XSI or Max in those, logically.
What the heck the editors being done lately for irrlicht are probably much better that some midcost game making environments I have tried lately.
Is more the need of good artwork than the need of good format: you can produce verrry nice things even with much crappiest formats than irrlicht supports at this moment, even of soem versions ago (and now, irrlicht is one of the most gfx formats friendly engine out there... )