Kinda of, but if you could SBR a FCU you could swap it between an Ar-15, Ar-10, or put a stock on a handgun. That's absolutely a perk of lower receivers but if it was the FCU that was the firearm instead it could be even more flexible. Currently you can SBR a Ar-15 lower but then you're stuck with just AR compatible parts, with a FCU nothing would stop companies from selling pretty much most types of firearms that accept that FCU.
20rd magazine is nice for a duty pistol. Jury's still out on the proprietary trigger group. May be hard if not impossible to change trigger resistance.
The modularity is nice, especially with the serial # being on the trigger assembly.
The locking pin mechanism seems cool for the RDS but I'd have to know more about it.