I've had my Sprint branded Diamond for about a week now. Changing my plan was not a prerequisite to receiving the $249 price tag. Although one Sprint representative I spoke to tried to coerce me into upgrading from my $15 Data plan to something more expensive (cant remember which one exactly). I was NOT trying to hear that shiet, and was adamant about keeping my current plan...so I said, "no, thanks" and hung up.
I called back again, got a different representative (sales rep., i believe it was) and ordered my phone problem-free, without any insistence that I change my plan. Go figure. I should also mention that I was eligible for an upgrade ($75), but I managed to talk the rep. into giving me the full $150 discount, plus the $100 MIR. And last, but definitely not least...I even managed to get a $50 credit added to my account AND a PERPETUAL $10 credit off of my bill every month.
The Diamond is already a beauty, but the hook-up I got made it THAT much more exquisite.