Update:
Good news, OptionBasedEffects can do what I wanted to do (update UI behind-the-scenes etc) ... and I like the look and feel of it better than WinForms.
minor snag: can't get the OptionDoubleVectorPan control to work, wondering if anyone has used it in a plugin.
OptionDoubleVectorPan(OptionNames.VecPan,optContext,0.5,0.0,1.0,0.5,0.0,1.0),
gives me a System.OverflowException: Overflow error.