Chris: can you move this thread to the correct place under "motorized systems"
Answer to the question is: you can get very good H-H motors AND actuators for this size of dish. I have an H-H on my 1.2mx1.35m Gregorian. Works fine.
I'm not aware of any fundamental design or performance issues that would mean one is more suitable than the other. Just don't use a DiSEqC motor since (a) only now are models appearing on the market that are even capable of driving this size dish and ( they tend to be significantly slower in tracking the arc.