The ZDZ 80 is a sweet engine, especially for the price. It shakes some, but less than a couple 3W 100s that I've seen. Very reliable engine. JohnVH has a couple vids of his Sukhoi with a ZDZ-80 if you want to see one in action. By far the smoothest twin I've seen is the GT-80, but the ZDZ will give you more thrust for hovering and other maneuvers. The DA's smoothness is between the GT-80 and ZDZ-80. I haven't seen any ZDZ-100s so I can't comment on them, but if it is the same quality as the 80 then you'd have a winner.