Importing FullFat (even if it requires changes, like converting to kmode) is still WAY faster than developing a new one, based on MS sample code. As we know, FullFat already works, so the testing procedure would be significantly shorter, compared with the one being written from scratch. Finally, FullFat author agreed on colaborating, effectively helping out with the adaptation process. For the new fat driver, we`d still require at least developer, either someone from ReactOS team or outsider.

Again, i dont see developers hanging around, waiting to do anything for ReactOS.

So its a choice of ready, funcitoning code and tested, that needs to be adopted, as well as a new developer, eager to help us out. On the other side, there is only a reference MS code, that potentially (even if we`ll be able to actually write a new FAT driver and test it) someone could use as an excuse to question the new driver and spread FUD about its similarity to MS code. 

We already have seen it... Advangates? I dont see any.

I think that the present need of working, fully featured and stable FAT driver doesn't need any explanation