To start, I have made the same switch in BB from Nextel to Sprint recently. Sad to say though, I have not been having any issues with the new 8830. I love it!
Now to the customer service part, I can tell you there is and will always be problems with Sprint CS. When I had Nextel I didn't have any complaints with their CS. One thing I have figured out is that when you call Sprint CS about a BB, ask to be connected to BB tier 2 support or higher. The basic CS person has ZERO knowledge of a BB, for the most part. All they do is look at a trouble shooting flow chart and turn pages in a book. BB tier 1 are a little better, but not too much from my experience. Heck, I could give you my phone number and help you better than they could, so could 90% of this forum! Tier 2 BB support are a lot more in tune with the BB. Mostly due to they usually own a BB.
Again, this is just from my experience and knowledge. I always ask every CS rep I talk to if they own a BB or ever messed with one. If they say no, then they get a polite "Push me up the food chain!" reply from me. I usually am not happy talking to a CS rep unless they actually own or have owned a BB. In my mind it shows they actually have SOME knowledge on it, which tends to be better than the CS reps you get when you first call in. Now I wouldn't go asking or demanding to talk to Tier 2 BB support over a bill problem, but I have had great success asking. Matter of fact, I'll give you a little example from when I switched from my Nextel 7520 BB to the Sprint 8830 BB. the first girl my call went to had a slight attitude that day right from the start. I went through the motions of telling her I needed to active my phone and what have you. As soon as I said BB she started sighing and huffing, so I politely ask to be pushed up the food chain and got a manager. It just so happened she was a fellow crackberry addict and she had heard of the forum, which I promote to everyone I see with a BB (where is my BB forum paycheck? lol!). The nice lady told me that she had once been in the tier 2 or 3 before, can't remember which one I was just happy I was talking to a CB addict! anyways she walked me right through it, gave me some extra pointers and stuff, and off I was enjoying my new BB. Moral of the story, act politely, be honest with out sounding like an a$$h@le, and you can get decent CS support.