I still use them for practice and if it is new or in good shape I'd use them for a local match. Good guns are expensive, so I do what I can.
But, at an Area 1 match a few years ago, a buff cost me a complete stage. (gun locked up on the first round) Barely got the gun apart and ready in time for the next stage. Probably wouldn't have made it if my Brother hadn't helped me. That gun was totally locked and we both worked up a sweat getting it to open.
I won't be running a buff at any major matches ever again. For a few hundred rounds, it won't make any difference.