This has been covered in many many other threads.
I have not been on the forum for most of the year, but if you search "Joe Johnson six wheel" you will find 2 pages of threads.
In my opinion, six wheel drive should be the standard drive system by which I mean that if you don't have a good reason to use something else, that is what you use.
Bottom line: good balance between weight, traction, and turnability.
Read the old threads to learn other view.
Joe J.
P.S. I promised myself that I'd put in a shameless plug for the
"NBD: Nothing But Dewalts" whitepaper whenever I posted in the 2005 Season, so here it is: I believe this instant classic will take its place as one of the most important How To's FIRSTers have access to. JJ