In all honesty, it's just a subjective rating given by Artsci.
1 = operational but less than ideally
5 = nominal operation, just works, nothing more or less
10 = works all the time and if not the owner leaves the breakfast table, rolls out his dedicated Bell Ranger 407 to whisk off with his team of technicians to immediately fix the issue
KF0OS/R Repeater Detail Report
A rating of 9 means the repeater owner probably doesn't have the A-Team at the ready, but is very responsive none-the-less...