Also want to see how it goes on Ash and flame maple after grain filling/popping with timbermate and before tru oil.
Isn't that kind of redundant? Isn't the sanding sealer meant to fill the grain? So why use the Timbermate as well?

In your experimenting, maybe do a test to see if the FW SS can be tinted with Prooftint. What's the worst that could happen???