The distance on the 16-46CS+ is 1 7/8", or maybe 1/32" less than that (i.e., 1 27/32"). Don't know if they used the same spacing for the PCi's, though.
All depends on what you're trying to stuff in there.
Actually, it is a (minor) issue for SVSs with binding posts (CS/CS+/Ultra) since the binding posts point straight down from the end cap, and the narrow clearance makes the use of banana plugs impossible. Some people find that annoying. To me, it's just a charming quirk.