What are you using for On set live preview keying? I have an app for mac that I used prior but I have no mac anymore.
Features I like.
Live keying
Transforms so that you could scale the keyed layers to fit i a new background image if needed.
Options to overlay guides, even handrawn guidies.
Tools for getting a very even green/blue screen. Not counting just a waveform.

I was thining about Davinci Live but it does not seams to work.