Wow! Thanks for all of the input. I've decided on the pumpkin colored tractor. After crawling all over both, the Kubota has quite a few things that are just...nicer. The spiral bevel gear FWD; the front driveshaft tucked into the oil pan, vice exposed; plus, the seat and operators console fit my 6'4" 250 pound frame much better. Now it's just a matter of horsepower. I'm leaning strongly toward the L4400, because I figure if I need the power, it'll be there. The L3400 is about $4200 less expensive though, and that's a consideration.
As to the new v. used question, yes there are numerous used tractors for sale, but I'm no expert on judging how well the machine has been maintained etc. I've done maintenance on my diesel trucks, and on my other vehicles, but how someone has maintained their equipment is a large question mark that I don't have the expertise to judge.
I've always bought new automobiles and trucks, and then kept the vehicles for 10+ years making sure that they're well maintained, and keeping the documents for resale. In this case, there won't be another tractor in my lifetime, at least not for working the land, so making payments for 5 years, although painful, is an easier pill to swallow than trashing my savings for a used tractor that will cost almost as much. I peruse tractorhouse.com quite a bit, and most of the newer CUTs seem to hold their value very well-or else the owners are very proud of them. The one's under $12K seem to be pretty well used.
As to the "free money" line, interest rates are by definition the cost of money. Borrowing at 0% when inflation is officially at 6.5% is actually better than free. Kubota is losing on the money because it's getting paid back in currency of less value over the length of the loan.
Anyway, thanks again for all the input, it has been very helpful.