Do you have that many RPis now, that you need more than a /24 network?!
Yes/No/Maybe :$
It's mainly because I'm going to making use of a number of ESP8266 devices and it would be nice to have them organised together in a separate range.
I'll hopefully be removing one RPi from my setup and replacing it with an ESP8266 at some point once I paint my desk and get my "office" back in working order.
Dunno if this helps, but my wifi router does 192.168.2.x, and my tablet can see local webserver @ 192.168.1.x (wifi & server both to same wired router)