Installed Hypersphere's silencing rings in the Realforce RGB today. Out of the box, the sound is pretty disappointing. The upstroke clunk is loud and reverberates in the case quite a bit. It gets annoying pretty fast. It's not anything like the solid sound of previous Realforce boards. However, after installing the Hypersphere rings, it's become a joy to type on. I don't have any experience with any other silenced Realforce boards, but I do have an HHKB Type-S. The silenced RGB is quite a bit quieter and definitely has less thock than the plasticky HHKB, but it's still enjoyable and has the signature snappy Topre feel.
Also worth noting the RGB's switches are extremely smooth with no grain at all. My Type-S switches have a disappointingly rough and grainy feeling.
I did notice that if I put my ear close to the board there is varying degrees of ping coming from the springs in about half of the switches. I am familiar with the Topre pinging issue resulting from misalignment of the springs inside the domes. I did not remove the domes from the PCB and I took extra care in the alignment when placing it back onto the switch tops so as to avoid any pinging issues. I have disassembled the HHKB several times without issue, but despite my best efforts, there is some pinging. It is not noticeable unless my ear is right up to the keyboard.
The pinging may very well have been there prior to disassembly, but I was unable to hear it due to the absolutely obnoxious upstroke clacking of the unsilenced board.
I'm quite happy with the result. Special thanks to Hypersphere for providing his silencing rings for the community.
Here is a recording after installing the Hypersphere rings. I didn't bother making a recording before. You can find examples on Youtube if you're interested.
I used an Audio Technica AT2020 placed approximately 30cm away from the keyboard to capture the audio. Sorry for potato video quality (my DSLR doesn't do video).