I dont like to compare them because of the difference in construction methods,the UCD is crude compared to ST. But I do miss it , you get used to that slow /stable flight, when you switch planes, you really notice the difference. However, I think the ST will help me forget the UCD. The only weird thing I noticed(and forgot to mention) with the ST is it flys nose high some times,like its too tail heavy, but when I throttle down it drops right away and with the nose down. It lands normal too. I need to fly it again to check inverted flight&elevator required to level it. I wonder if that is what you are seeing? Last night I checked a few things on the engine&fuel tank, all looks OK so I swapped out the Cline regulator and check valve, the check valve I was using lets a lot more air thru it than the others, wonder if it was loosing too much crank case pressure,not sure what crank case pressure does? I hope that does it, I need more S H O W T I M E!!! (where is your cg at?)