The 6500 machine is good machine.
The 6600 was the updated version and certainly a few more things that you want in it. I believe the AccuFeed is not on the 6500, and after having the 6600 with it, I would not recommend the 6500.
You've compared your price, and already can see that you are not getting a big drop in price from a new one. Take your research a step further and compare the price to the 6600 ..... and further still to the 8200 (or is it 8900?) which is the newer and more updated model.
Of course, only you know what features you "need" and are willing to pay the extra dollars for. But sometimes going a little further than you "want" will keep you from an upgrade for longer .......... and in the end that is all a savings to you!
As for the salesman ... if you are already not comfortable, really think twice! Ideally you will have a long relationship with this dealer, and if you are uncomfortable now, will it get any better, with him or anyone else in the shop, as often times, the atmosphere is the same from one to the other.