That last sentence definitely has a lot of truth to it, and these new ones are more productive and much better on fuel, sometimes it is better to bite the bullet when you can, running older equipment does have it's price, but is also not the end of the world for moderate to light use.
Comparatively speaking, we went that route at our place with the horses, they bought a new 30 HP Challenger with a loader and a rotary cutter. We also have an '80 3600 Ford diesel and I've got the old 850 at home, they all work well, the new one is smooth to operate, but it'll turn over easy without loaded tires, counter weight and being careless. The older ones are by far heavier built, and have that feel about them, the ole 850 is no joy to run while mowing in the hot humid weather, but nonetheless it does the job, it will out lift and out pull that new one, not exactly the same HP, but I'd prefer it for many tasks, it's just more stable and in 5 years the only break down was a fan belt, and it's been hammered way before I got it. The 3600 has lots of torque, it too needs some work now, but I'd not see it gone for anything, these are great utility tractors when in good running order, but probably the best advice is the owners preference, budget and economics considered for their application. No doubt you can easily dump quite a bit into one, on the older hundred series, wasn't external_link offering ground up restored base model 800's for like $8000 ? You could get a lot of years out one of those with no headaches if done right, bump up to the thousand series, what's it going to take $10,000 at the most, (being generous here)? The 30 HP challenger was like $20,000 and it's had it's shares of petty but annoying things to deal with, no stack, filter soots up, bolts keep loosening, loader frame bolts popping the heads off, and it's not abused.
Hard for anyone to say what the most economical decision actually is, and it's really an owners preference new vs old. If you had to make a living with it, no hesitation about going new, you really have no choice there. I spent a day on a late model M-F 1530 with a loader, handling bales, much heavier than the 30 hp challenger we have, a little bigger, loader frame is also much heavier, not a bad tractor to consider, and a good size in comparison to utility type tractors of the past. I'd have a hard time passing something like that one up, except to avoid the financing and payments. What the heck, find something with low hours,not abused save some $$ there and if the payment gets out of hand, put it up for sale.
Makes a good discussion here though.