Wirelessly posted (BlackBerry 8700c: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0) BlackBerry8700/4.1.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/102)
Once you switch to Cingular, you definately won't regret it. The only question is do you really want to spend all that money to switch. You said that you have been with Sprint for 7 years, well what would a few more months hurt? You would save a whole lot of money if you just finish out your contract(s) with Sprint then make the switch. Then you could do what someone said earlier and sell your Sprint phones on eBay and probably make enough to cover the charges for the Cingular phones.
But I made the switch to Cingular from Alltel and I haven't looked back. Coverage is 100 times better and contrary to what several people have said on here, I've had no problems with customer service.
LG9100f > 7280 > 8700c > HTC 8525 > HTC 3125 > BlackJack > HTC 8125 > Curve 8130 > Bold 9000 > iPhone 3Gs > iPhone 4 > Torch 9800 > iPhone 4