Hello Im new to Nestopia but I was instantly impressed. I prefer it over VirtuaNES too. However one important thing its missing imo is rerecording support.
Some players are creating TAS (tool assisted movies) and its a shame that FCEU is the standard in that area. I think VirtuaNES would could really improve that scene with rerecording support. http://bisqwit.iki.fi/nesvideos/
An alternative, but im not sure how feasible it is, is to support the other emulators movie files (FCM/FMV). Or ahve some sort of translator/convertor. This way one doesnt need to rerecord in a new format.
Keep up the good work