There are a few differences that are rather minor, just little things that are incorporated into a new production model. The really BIG differences are the addition of the true hardware BLIND SCAN capability and the true support of dual tuners. Beyond these electronic alterations, they are virtually identical. The new physical layout of the HDD bay and supplied connection features for the HDD are a definite improvement, too. This is very nice! You don't have to remove the entire cover, just one little plate to access the HDD bay and the connectors are right there for you. This was a small, but very appreciated design change.
Just to note: Both the Premium (original) and the Premium Plus have WiFi. A great advantage, having WiFi!
I have the plus now but need another. I saw on AzMiami the plus is like 450. I thought I paid somewhere in the mid 300's for the one I have. I about fell over. I bought the current one off one of the other Miami dealers from Ebay.
Oh well I guess I have to decied wheather I want to spend the extra for the plus or just stick with the premium.