Hey Sharkey,
Speaking from experience, I love C5. I first applied it to me A1's wheels in September last year, ready for winter. Right through till April (when I sold it), it was still beading water on my wheels.
To answer your question, it made wheel cleaning far easier, I found I don't really need a big wheel brush to agitate dirt, just a small one to lightly brush & get in and around the bolts and centre cap. Gtechniq claim up to two years of durability. However, these things are always subject to conditions, mileage etc, but I'm a heavy (makes me sound fat!) driver and found that with a pressure washer most dirt falls off after each wash. I still use a a spot of Bilberry wheel cleaner and once a month some IronX, but it's an easier task.
Hope this helps
Matt.