Agree also. I think the X series cameras are like improved, digital equivalents of the old Kyocera Contax G2 (X-Pro1) & Konica Hexar AF (X100). Those were niche cameras for folks who wanted many of the advantages of RFs, but couldn't afford/didn't want to pay Leica prices or wanted new features like autofocus. So while they have some of the advantages of both dSLRs & RFs, they also share some of the disadvantages of both, & as others have noted, they're not exactly cheap.
Based on my own experience & that of friends who tried & ditched the X-Pro1, I would say the lackluster, compared to a dSLR, AF is indeed the greatest hangup, especially since the alternative of the EVF is not quite there as far as providing a dSLR-like experience. I can make the X-Pro1 work for me (just like I can still work my G2), & will keep it as a backup for my 240, if or when it arrives, but it will never be my primary digital camera because of its pokey/erratic AF performance in low light, which is 90% of my digital shooting (same is true for my D700). If I shot digital a lot during the day, it would be perfectly suitable, but its AF doesn't fit my available darkness needs. Overall, I believe the type of photographers who are looking for a Leica alternative tend to be serious amateurs who are very picky about their equipment & are obviously willing to churn through gear in search of the right tool.