:pint: Hello, Crestfallen, and welcome to Amiga.org!
;-) As I understand it, most of the OS 3.1 features do not require the extra bits that comprise the difference between Kickstarts 3.0 and 3.1. However, a few of them do. Running OS 3.1 on KS 3.0 is very common, but occasionally, you'll get errors due to this, but I couldn't tell you what they'd be.
So, it's best to get real 3.1 ROM's in the long run, but it isn't really urgent.