I had and still have the SLDR driver and it rocks. Great driver. The R1 is not the end all be all. Yes I have the black driver cuz I could. Does it help, yes. Are you at a huge disadvantage not having it. No.
I had the SLDR through the better part of my Legend career and I was able to compete with pretty much everyone. If I lost it or didn't shoot well it was because they were better than me or I was off, not cuz I was 5 or 10 or even 15 yards shorter. I could still win RGs and place well in free tourneys and beat players in match play.
I think the bigger issue is that you have the G20s. Good clubs but with the 85 Nikes and the R11s available to you, I think that is the bigger issue. My scoring potential and game changed when i got the R11s. The long irons are ridiculous. I get that maybe the meter is a bit too fast for some, well now there are the 85 Nikes, which have same meter as the G20s with half dot more precision and more spin, I believe. I rented them and was able to do well with them. Stuck with the R11s, but i want the higher level Nikes instead.
Think you would find your scoring would improve if you dropped 3500 credits on irons, not a Driver, but yea I know, you been around the block and don't need any advice on equipment. However, a 20 foot distance from pin average, coupled with 36 percent sand save, 48% scrambling, and 34% one putt are all bigger issues and would certainly save you strokes faster, if improved. Unfortunately, a shiny new LIMITED edition R1 driver is not going to have a huge impact on any of those.
Just my two cents or pence or colones or whatever, although I know you don't want to hear it.
I do believe it will come out again soon though, so might want to get the levels moving so you can get it if they do. Its a huge money maker for WGT