In reply to mutt:
Assuming all the usual caveats of responsible access there's absolutely no issue with you doing it from an access or environmental standpoint.
However, I've done it a few times and depending on exactly what you're doing I don't think it saves much time.
Going up the footpath from the North Face car park is a bit of a slog and I don't think it would be much fun with climbing kit. Going from Nevis Range is easier but much longer.
Coming down the normal path to the North Face car park is obviously quicker than walking but it's so steep that you're just riding the brakes all the time.
Post edited at 12:51