I'm of similar strength, and I have occasionally been informed that some account got banned for cheating (you receive a notification because the system restores your lost rating points after that).

But it's definitely affected less than 1 in a 1000 games for me. Of course

I might have still gotten beaten by cheaters that went undetected of course, especially if they stopped cheating or lost interest in the whole thing leaving the site before they'd get caught.