I've seen lots of L7s who have never gone for promotion who are better referees than some L5s, so if I have a big game that needs well handling I'll look at who is the best performing rather than necessarily just who is the highest level.
This is absolutely true as well.
This may sound a bit snobbish but I don't think it's hard to get to L5 and is something any semi competent ref should sleepwalk (If they want it). That leaves plenty who make it there and are considered 'good' for being L5 when in reality they're far from it.
Perhaps a touch harsh...