Not very popular, priced to high?
Well, initially, yeah, but the problem was that Leitz wanted an SLR that was as quiet as an M, and that took some pretty sophisticated doing, including mechanical damping of the mirror and so on, not to mention the thing is built like a tank.
Plus it lacked some features that less-sophisticated but also very rugged cameras like Nikon had -- interchangable viewfinders, a wider range of accessories, a better world-wide support system.
So Leitz lost money on every SL and SL2 it sold, despite the high price, which is why it quickly went to the joint venture with Minolta that produced the R3 and so on.
Interestingly, DAG told me that, even with the horrendously high cost of production, Leitz tried to cut costs. If you look in the lens mount you will note the tiny screws in there are phillips head, to speed up and make simpler the assembly for the lower-paid folk in the Portugal factory doing the initial work.
Damn good cameras, though.