I would, and did, go with the R9. On a drive, precision isn't as important. At least until I started playing Congressional a bunch, my driving had remained pretty constant after the upgrade (around 85%, now 80%... Congressional is just a long, tough #$%^ course. In the Open, I wouldn't be surprised to see the winner shoot mid 60s), even with the faster meter. The R9 is more forgiving, so unless you miss the ding in the direction of a strong wind, or on a side you have cut close, or you miss BADLY, the R9 will put you in the fairway farther than the G10. Also, the one big advantage the G10 does have is it's loft. But that is mitigated by the length of the R9, which as mentioned is much longer than listed. It lists at 275 but I would estimate that a good 90% of my drives top 280, and at least 50% 295+. And it flies exceptionally well with full BS, even into a light wind, which mitigates the lower loft to a large extent. I have been extremely pleased with it, and I just went from the level 47 Rapture to the R9. From the lower Rapture, you will notice an amazing difference once you get used to the faster meter.
To really break it down, here is what I would say: If you feel like you are going to hit the ding regularly (say 3 of 4 or 4 of 5) with the meter of the G10 and R9, then get the G10. But, if you think you are going to be within a couple pixels of the ding 80-90% of the time, but only actually hit it say 30% of the time (like myself), go with the R9.
But for irons? G10 FTW. I chose them over the TP and R9s,and I couldn't be happier. If I could only find a putter that would improve my green game as much as a new driver and irons improved my tee to green game.