I've been using BitPim for several years and while it is by no means pretty it does what it says it will. It has allowed me to back up my Sanyo MM-8300 (and an MM-8200 before it) cell phone with no hassles. It looks like it was laid out by a PC or Unix person but it works well. Doesn't have the most intuitive user interface either but it gets the job done.

Without it you're basically stuck on a Mac as Sprint centers will tell you that you can't (or *they* can't) back up the phone to a computer. pshaw! No more re-typing contact numbers again.

Also have never had issues with BitPim crashing.