Like you I have found increasing motor size makes a big difference. As the hot-rod enthusiasts say "There ain't no substitute for cubes".
I replaced a 1.5hp 3ph mill motor with a 5hp and VFD and a 2hp 1 ph lathe motor with a 5.5hp dual speed motor and VFD. Both are a huge improvement.
Here is a post on my mill heart transplant. How to make a 6000rpm Bridgeport.

i like your night class reference for programming VFDs. Most are not difficult to do, just very very tedious. Understanding what to set many badly described parameters to is very difficult. Some units have over 100 settable parameters.