If you look through RFF, you will find many active users who regularly shoot with Nikon RF cameras.
I shot Nikon RFs for newspaper work in the '80s till my paper went digital in late '90s. They are different from the Leica system but not necessarily inferior. I was using personal gear to augment the company-issued SLRs. I appreciated that the Nikons were cheaper then than Leicas and offered outstanding optics. The 35/1.8 is called expensive because it costs $500 - $1,000 in user shape, but what's the price of a fast f/2 35mm lens for Leitz? The bayonet lenses change rapidly. The focus wheel requires some getting used to, but once learned is a handy feature that allows one-handed shooting ... the first time I climbed a tree to take pictures after a major wind storm, I was sold on one-handed operation. The ergonomics are classic Nikon and make it easy to switch back and forth with an SLR. The flash syncs are a standardized 1/60. They never need a CLA. The 1:1 viewfinder is, for me, superior to the miniturized finder on the Leica system. You can shoot with both eyes open and feel like you are a part of the scene. The secondary window on the SP allows an eyeglass-wearer to comfortably shoot the full range of lenses ... 28mm to 135mm. The 21mm Contax lens of the 1950s was optically unsurpassed and quite affordable compared to Leitz 21mm glass. The lifesize 35mm view on the S3 is worth risking scratched eyeglasses ... it completely changed my relationship wiht 35mm and 28mm lenses. The 1:1 viewfinder makes shooting 85mm, 105mm, and even 135mm lenses a breathtaking dream, and these three in Nikon RF mount are among the best pieces of glass ever produced by anyone, anywhere.
I tried Leica's a couple of times but considered them too different from my Nikons. And collectors drive the prices up to unreasonable levels for the work-a-day user.