They are right about the internet service. The dropped calls is mostly if you are moving about. The unlocked phones may drop as you move from one cell coverage to cell coverage area. But it will be a rarity.
Most (all?) of the cellcos only allow internet access via locked devices. No hard rule there.
I'm currently using a RAZR with Cingular - contemplating buying an unlocked PEBL off ebay (my razr is starting to go)...the customer service rep at Cingular warned me of dropped calls and lack of internet service. Is this a scare tactic?