Please Explain the Sprint Upgrade Policy

[johnnycakes2]

Here's my situation:

I'm currently using a Mogul and ready to upgrade. I'm looking at either a TP2 or a Hero, haven't decided. I have a $150 upgrade credit as I am off my two-year $30 SERO contract and now paying month-to-month.

When I go onto Sprint's website and look at upgrading, it subtracts the $150 from the total price of the phones, i.e. $549 for the TP2 and $479 for the Hero. Was I wrong in assuming the $150 came off the $349 and $179 prices respectively? What's the difference if I'm a long-term customer using this upgrade credit or some stranger walking in off the street and buying one of these on a new contract? We're both getting the same "deal." What do I get out of it? Either I'm misinterpreting the whole thing or I'm right on the money and the system sucks.

Can anyone clarify this?