My last Do (.60) is my 5th one, I used a little rudd-ail mix for roll coupling, wasnt perfect but the thumbs could handle it from there.As for the KE & pitch coupling, my thumbs could handle that too, once you get used to it, you stay ahead of it. I liked my Do as well, took some flak at my local club for it,now that I have some 50cc's & a Fusion, they asked me to bring the Do & burn it in our next campfire!!!
It's still flying but the Fusion does almost everything better, less work at it, better thrust/weight. However, with some mixing(magic & mirrors,smoke to some)you can do true square loops, inverted flat turns very low, very slow HE KE, & some are doing rising inverted flat spins, not bad for $150 bucks on sale. And like one guy said-some dont mind "tinkering" around to see what they can make of it.