as far as buying referbished you **MAY** be better off. A refurbished unit is gone through with a fine-tooth comb to find any problems, they are facorty restored to new and come with a warranty. More attention is placed on a refurbished unit as one that comes right off the production line.
Note there is a difference from purchasing a referb from an authorized dealer vs. just any dealer.
That issue aside, go with the Marantz. It has all the major feature sets and expandablity one could ask for in a new receiver. The unit is simple to use, OSD is great, has great sound and great looks, not to mention the steller remote which i just love.
I too have the 7500 and cannot be happier with it. Sure the 8500 has what - 15 more watts/channel, not much to brag about, if you want to brag, get and external amp and use it for your mains. I have a QSC MX-1500a amp (THX certified)
(for what it's worth) and 360 watts/channel that will do more than most will ever need for HT.
In any event, good luck in your purchase and remember, have fun