I agree with everything skccvb says above. The transition to Masters tier is like a slap in the face in terms of adjusting to distances. You will be hitting longer irons and finding yourself with longer putts left and right without the stopping power that is inherent with short irons. It took a lot of time, but I was able to start getting respectable scores again, even without a club upgrade.
I originally debated the R11s or the K15s, eventually going with the K15s because of the slower meter speed - they seemed nearly identical otherwise.
Since then, I went with the full G20 set and after only a couple of weeks, I can say a few things about them overall:
- The meter on the G20s is slower than your R11s - expect to have to adjust, unless you're missing the ding right with your R11s
- The G20s are about half as forgiving as the R11s - the more off the ding you are, the more variation left/right in the shot.
- The higher trajectory means the wind will have more of an affect on the flight of the ball. The same is true about spin, at least for me. This has been the hardest adjustment for me with the irons is judging the difference in wind adjustments and distance based on spin.
- The higher trajectory adds to stopping power that I've noticed - the K15s are also the med/high. Again, still making adjustments.
I chose to buy the set for a couple of reasons. If I just had the driver with my K15s, there would have been some tough gaps to fill here and there. Also, having the same meter speed across all my clubs was important. Trying to go from a faster driver to slower irons back to faster driver was not something I wanted to do.
You're already using the three-wedge approach, which is a good path. My current set of wedges has me at distances of 85, 65 and 50 yards, but with the full G20s, I'm thinking I might move to 95, 75 and 60 to better cover distances under 100 yards.
The approach I took when making a final decision was looking beyond Master level and what would take me the furthest. The 5 yards may not seem like much now, but every bit will count in the long run. Plus, it gives you that much more time to get a feel for the clubs which will be the most valuable thing when hitting the higher tiers.
The driver will definitely make a difference - in the long run, though, getting the full set may make an even bigger difference.