I still have my original 1977 Troybilt Horse with Techumseh engine. The original Troybilts (before being bought out by MTD) still sell for more than I originally paid for it. If you can find one, even if the engine is bad, they are worth it. A friend has put new engines on a number of them in recent years. Many common brand horizontal-shaft engines will fit perfectly. Except for the belt, tires, tines and rear pulley/clutch, virtually nothing else ever breaks or wears out. Parts, including decals, are still readily available.
Whatever you consider, definitely go with a rear time unit. As you've found, a front tine will beat the life out of you.
Bar tread tires are far preferable to all others.
IMO, unless you are doing about a half acre or more, a 3-point/PTO tiller is real overkill, and quite impractical with raised beds. If your garden is fenced, it also takes a lot of turning room, which limits what can be done.
The specs on that Cub Cadet look pretty good. I've just been burned by some Cadet Cadet products about 8-10 years ago, and I have become very wary of their support and quality.
