I make substantial use of replay to test ideas and fine tune my skills. I would imagine many others do likewise. Please implement.

I second.
Sierrachart is preparing to run on Linux (already runs very well via Crossover), but there are no currently good competitors that I know of that run natively or even well on Wine.
Though this would get Linux users such as myself on board, I can unfortunately I see that there are other priorities at this moment .....and probably easier to tackle ....