944 don't rust easily, it's fully galvanized, so they don't rust unless damaged.
And I don't think you should compare 928 with 944. They are totally different. 944 are much lighter, and have only half of 928's engine. 928 is GT car, perfect for autobahns
944 is perfectly balanced and is really fun to drive, although not very fast. It's not a drag-racer, so if you like to show off and race others at traffic lights, it's definitely not a wise choise. And engined can not be really tuned much. If you into that, look for turbo, it can achieve pretty impressive performance with not much modifications. But suspension is great, even better if it has thicker sway bars than base model. I'll be installing ones from turbo next summer, small investment - big difference
If you deside to buy it, check clutch and tranny, these are ridicilously expensive parts (I feld the pain of paying for replacing clutch myself). Otherwise it's not that expensive to maintain. Even better if you can perform small tasks yourself. So you don't have to go to Porsche dealer every time you need to change oil or brakes. And mine is consuming like 10.5liters / 100km. I think it's affordable...
P.S. And yeah, timing belt should be
definitely changed with proper tension-tool. It's the first and most important thing after buying a 944.