I was trained in the R22, and would offer this for consideration. If you EVER intend on instructing as CFI(H), then you should train on the R22 because of the stick time requirement in Robbie.
Otherwise, I here the 300 is a better training platform. Also, if you plan to lease your aircraft, you should find out what is available to you in your area and where you travel. Finally, check rental requirements from different places.
I believe Robbie places that rent out aircraft require 100 hours PIC in R22 + Safety Course IF they are insured by Pathfinder insurance. Many places don't use Pathfinder.
Personally, I like the speed, altitude, and performance of the R22 over the 300CBi or 300CB. Having that said, I wouldn't limit myself if I had other options (there are 3 Robbie outfits within an hour of my house, but the nearest Schweizer is 3.5 hours by car).