I've got the MX5000 predecessor to the MX5100. Tranny is 8x4 on the 5000 and that's been plenty for bush hogging and my LIMITED loader work.
For LOTS of loader work, I'd go with a Hydrostatic transmission. The productivity edge is definitely there, there's no clutch to wear out and it's easy to be safe and precise. Haybaler9 got it right with the L5240 HST; great choice. Another consideration might be the L4740 HST. All four tractors (4740, 5040, 5100, 5240) have the same basic 148 cu. in. engine. The 5100 and the 5240 both have turbochargers. Don't think the others do.
Bob