The Raptures should get you to tour master but you'll have trouble holding the greens with them after that. When you are playing long irons into the green the Raptures don't fly the ball high enough or generate enough spin to stop quickly.
I suggested them because the OP's level is almost high enough to get them so they'd be a quick fix for lower scores, plus they really are nice clubs. The downsides are the lack of elevation and spin, plus the slow meter won't prepare you for the clubs you will need if you want to compete as a tour master and beyond. It looks as though the forthcoming higher level G20 irons might have a nice slow meter though so the jump wouldn't be so great.
alosso:
My question is, what will I miss, when will I have to change again if I buy the "easy" Rapture clubs?
To answer this, you'll miss being able to stop the ball dead upon landing. Either you'll have to figure in the roll after landing or learn to putt great.
You'd likely have to upgrade when you reach tour master. It isn't essential though, there are legends who got there with Raptures.
If you're really just playing to have fun and aren't interested in reaching legend in a hurry you could play the Raptures forever. I rented them when we had the last free rental weekend and it was great to play them again after so long. In all honesty I think I enjoyed WGT most during the time I played with those clubs, it seemed a lot more fun back then.
If you want to be more competitive then the G20 are going to be a better bet.