Well after talking to Richard I think the best idea is to wait to work on this until I have a lot more time to mess with it.
He did give some good suggestions such as using the LM3409 instead of the MAX1620 buck converter.
I do still think that a buck driver is the best option for 4s voltages but for now I am going to focus on polishing up the FET 46mm version in this thread: Texas Avenger "TA" Driver series - Triple channel + Bistro or Narsil + Clicky or E-switch - The Ultimate open source driver!
It should work fine for the XHP50/70. I think a quad XHP50 Q8 with an FET driver will still be something to behold. Just don’t think that an XHP35 will get along well with the FET.
So thanks for your time, sorry to get ya’ll hopes up. I just think my limited time is better spent on other projects at this point.
I am real curious where the possibility of a triple channel Q8 driver goes.