The GT could end up quite a bit cheaper because the GT isn't limited production and Suby has been throwing incentives at them to keep the sales high. You can also find a slightly used one around. Of course if you really want to compare a GT to the MS6 a better comparison is the Spec B since it is also limited production and comes fully loaded.
A lot of automotive publications have mentioned the MS6 along with EVOs and STi but like it was mentioned before they are a totally different class. I loved the STi and EVO but couldn't commit to the harsh ride, immature look and high insurance premiums. I also think the MS6 does and doesn't directly compete with the 330xi and the G35x because they are more mainstream luxury cars rather then limited production performance models but they do offer similar performance for the money. (not to say people would not cross shop) The AWD system in the Mazda is a front biased system that needs slip in order to send power the rear wheels. Not a bad system but not ideal for high performance vehicles. (this really only makes itself known at high limits)
