I considered this as well and talked to Andy who said it would work well and had no issues even on race bikes. I ordered a couple of the chains and found to have clearance issues with the inner primary and stator bracket. The o-ring chains are slightly wider and the rivets protrude a bit more as well. Too bad because they are excellent quality solid chains. If running an open Manx style primary it would have worked well. Seems every bike is different in how the stamped metal primary fits together so you might get lucky? I ended up going with a belt drive in my Atlas and Domi build.
Scott
I also now remember that I was concerned about the lack of lubrication to the clutch bearing. I know it only functions briefly when the clutch is disengaged, but in the (sad) real world it's more often than not that you get stuck in a situation in traffic or at a light where have to hold the lever in longer than you really want toFortuitous time for your question, as I installed a 428DID X ring chain today on my Atlas primary..
I was having issues that I couldn't fix keeping oil in my primary, and as I use the bike fairly regularly got sick of the mess and top up.
My last chain was an RK non oring, it only lasted about 10k miles (ran dry, not a chain quality issue I don't believe).
One small issue you will come up against is the outer link plate on xring chians is effectively a press fit, but you won't fit your chain breaker/press in the primary. I just put the split link up against a ridge near the alternator and taped it down with a punch bit by bit until the clip would fit.
The other option would be to contect it all up (76 links) with the clip or rivit it, and then take the drive socket and the clutch basket off, put the chain on and slip it all back on, time consuming.....
I had no clearance issues.
My only concern is it will run to hot inside the primary case with the cover on, I figure I'll see how it goes and if it doesn't last I'll get a nice open primary and let that air in for cooling.
I was concerned that the velocity would be to high as well but then considered the following
From my understanding one of the factors (apart from pure hp/torque and abuse) that effects chain life is the radius and speed the chain needs to go around on the smallest sprocket.
Modern sports bike drive chains are designed to run at well over 200km/hr, with often a much smaller sprocket than my primary (17t v 21t), from my (very quick) calcs this results in a similar speed at higher rpm for a standard atlas (need to verify this).
I was going to run it for a week or so without the primary cover, and then see what the temp of the chain was and compare it to the drive chain. It will obviously run hotter once the cover is back on but will give an indication anyhow.