We had a customer put 60 hard (LOTO, Cumberland) hours on the 700/NXT set up with 0 failures! (not including human error)!!
We changed the tranny fluid once and gear lube twice along with 2 oil changes, other than that lots and lots of fuel!
Not sure what the benifits the #6 has over the NXT, but we put the NXT through the paces and were pleased with the results!