I purchased a used GG1 a few years ago and loved it. It was not R2R. It replaced a Denafrips Terminator Plus with Iris DDC and in stock form the GG1 performed on an entirely different level in terms of musicality. I am a super fan of Direct Heated Triodes.
I sent the GG1 back to Poland for upgrade to Engine11-P a year ago and can hardly believe the benefits. It is now essentially a GG3 on steroids.
If you don't like the R2R I think you will love the upgrade! I also got the new Volume Control and JL USB. I am not using the USB as I prefer the S/PDIF sound.
I am not positive but think all the GG DACs do DSD. I think some of the early versions had separate converters for PCM and DSD.