Kristopher, I'm not familiar wth the other Norvels. As far as flying is concerned I started with the LMH so I have no airplane experience. As Alan said Norvel doesn't mention vmax engines on their web sight.....and I realize that Norvel has a good reputation among small rc plane pilots. Lite Machines does claim that it is Norvel's problem. If you ask me I think the heli was underpowered with the vmax6......I know there are people who disagree. The vmax7 is a much more powerful engine and is a better match to the weight of the heli. Unfortunately we all know about the vmax7's problem. Also I don't know about collective pitch with the vmax7....is it powerful enough? CP upgrades will be available for the Corona..... and maybe the 117 if there is an engine and fuel system that will work.
Mark