I work a lot with dynamic cloth (basically only use it to be more precise :D)

Using conforming cloth as dynamic cloth is not really good as Poser have a very hard time simulating it. This is also one of the main reasons why it take a long time to simulate and crash.

Its crucial if you want to benefit and have fun with dynamic cloth that these are designed for it and most conforming cloth is not, its designed for making use of a bone structure. Therefore you can get away with a lot more mesh wise, because it will be controlled by the skinning (bones) and they doesn't care about overlaps etc. So when the simulation crashes its most likely because the mesh gets so screwed up that the cloth room can't handle it.

You can make thick dynamic cloth, I made a quilt and a pillow, which are dynamic, but it really need to be carefully designed for it, to make sure that the simulation doesn't take ages and crashes. You can see how i made it in my store.

But for clothing you need a single surface mesh and to make sure that there are no overlapping faces.

For me when I export I usually uncheck everything, but again those things I export are already designed for being dynamic, if its conforming I don't really think it makes a different. The cloth room is simply not working very well with just throwing in cloth designed for conforming.