I choose Randy G as an instructor for two main reasons. One, I could not find one single negative comment about him (from and former students and otherwise). I must have found comments/recommendations from at least 12 former students on this site. From that 12, I probably PM'd 4 of those students. The second reason I choose Randy was his location, which was about a 5.5 hour drive.
As far as how much did I expect my playability to increase....didn't know that one for sure. I felt my game was at a standstill, no matter how much I practiced and I was practicing anywhere from 30 minutes to 2 hours a day. I took those lessons about 6 weeks ago. League started about 2 weeks ago and I am off to a good start.....8 wins in a row and undefeated.
Good luck in your search,
Mattman