Did anybody keep their unlimited data from two years ago?
Verizon told me I could if I bought the phones straight up, although I am not sure I believe the CS reps. I would have considered it but they do not lower your monthly if you pay full price for you devices, so I would not have made up the difference over two years between my old plan and the new.
I paid about $520 for two new GS3s: 1@$150, 1@$200, 2x$30 upgrade fee, plus tax on the full retail price ($1200) of the phones.
Buying them straight up, I don't know if I would still get the extra $50 discount or be charged the upgrade fees. Figure about an extra $850 to buy the phones outright, divided over 24 months for about $35. My new (forced) plan with 4GB is about $15/mo higher than the old, so I'm still down $20/mo over 2 years paying full price (although I would have had unlimited data). Paying an extra $20/mo to go from 4GB to unlimited data is very tempting, but if you can't keep your unlimited data then I doubt Verizon is going to refund my $850.
Regarding plan changes mid-contract - I know you can make adjustments to a given plan (for example, I can change my data options). If worth a call anyway...