When it comes down to it, it is a "Multi Engine" column rather than an "Asymmetric ME" column. I have heard many stories of companies not allowing their pilots to count 337 time in their ME columns due it is only an In Line thrust aircraft, but I also know a lot that count it as multi time (as it is and should be imho).
And I have never been asked how much asymmetric multi time I have and nor have I seen it in any applications in the past, so I dont believe it is a big deal. In the end you are still managing two engines on a 337 and the only difference is really during an engine failure unless you are useless and cant push the throttle levers forward whilst keeping the RPMs level (not counting turbos boosting at different rates on T/O, but thats easily overcome also).
And to the original Q, I havent heard of any MTOW limits as to what counts as "ME Command" although I have no idea about ultralight twins.
My 2cents
