Okay, I'm not a programmer. That said...
Would it be possible to draw your own shape for use in the cookie cutter plugin? Or at least create a shape and import it as a psd, etc.? With the use of the feather function, this coul be very helpful in masking certain setups (I've tried to use the Mask plugin and I can't seem to get it to do anything I want). Besides, the nice thing about the cookie cutter is that it isn't based on color or mode -- it's just "here's a shape...see it or lose it..."
I think some sort of advanced masking and/or rotoscoping would be quite a boost for Vegas. Yeah? Nay?