Opinions on iOS feeds&speeds apps?

Like this one?

CNC perfectCut by ClaRo di Solaroli Claudio & c. s.a.s.

The app only costs 99 cents… yet I still regret it.
Not sure if I was just using it wrong, or if it scales up for better results but at 5000 rpm it pretty much spits out the same numbers no matter what the material.

Anyone found useable others?

Why not use G Wizard and its nifty MeshCAM integration?


@WillAdams Had gotten the impression that was Windows-only, but had another look now and am happy to find that I was wrong.