Every board I read is full of people bitching about iBill and CCBill (especially iBill) and it's true - they're total crap.
So, I switched all my sites to GloBill last month and... 1) The service is EXCELLENT, 2) The set up was free and easy, 3) The checks have come on time, 4) Sign ups are up 10% because their fraud scrub is better.
It's too early to know about chargebacks yet but I've heard from other webmasters that GloBill gets far less chargebacks than iBill.
Sign up here:
http://www.globill-systems.com/