Many of the H1 owners I have talked to, and some were consulted by AMG during the Alpha build, do not like the Alpha. They are more of the offroading type and say the power from the Duramax is nice, but the gearing and other features of the older H1s makes the power less important. Besides the cost of repairing a D-max to be much more than the good old GEP motor, the engine and trans is much more exposed and the ability to to field work and repairs is extremely limited.
Most feedback is to focus on a 2000 or newer truck (fixed #8 cyclinder) or an older model with a 2000+ engine replacement.
I would love to pic up a C-series. That would be sweet.