LOOK NO FARTHER.
I was priced (locally) a couple weeks ago for a Land Pride FDR1660 (5ft) @ $1575.00 plus tax. That was the only dealer that was that cheap. I called about 12-15 different dealers between here (LA) and Mississippi. Nobody else could come that close to that price. So, I think you are getting an Excellent price for that model. If I were you, I would go with it and wouldn't look back. You could probably easily run the 6 ft. but at that price I know what I would do. And hey, who says you can't try to negotiate on the $1600 anyway? I would at least try. But if the dealer says no, it would still be worth what he's asking.
As for the price on the FDR1672, I think thats definitely high. My buddy bought one a few years ago and absolutely loves his. He uses it for himself and commercially. All he had to do in the time he's had it was replace the belt 1 time. And believe me, he cuts A LOT of grass with it. The mower has paid for itself several times already and is still in very good shape. He does keep it clean and greases it regularly though.
I hope I've helped and again, GET THAT FDR1660! ITS A VERY GOOD PRICE AND YOU WON'T REGRET IT!
Travis R