I drove my SDL 45k miles for 5 years all over New England and it was perfectly reliable. We actualy took the SDL once on a road trip over my moms car because hers broke.
It always started the first try every time, and never skipped a beat.
The SD failed to start twice but both times were my fault. The first one was because I ran it to low on fuel, and the way the car was sitting in the driveway the pickup was out. The second was because it was to cold, and I let it sit at work all day. I should have gone out and started it every 3 hours or so, but I didn't.
If you go through these cars they can be as reliable as any modern car. They are very simple, only a few things will strand you. If your cooling system is in good shape, your filters clean, and your belts tight chances are they won't stop running. You have to commit the money to proactively replace stuff, like oil cooler lines so you don't get stuck. A lot of the break down posts on these boards can be prevented with some proactive maintenance. For example there is no reason an engine mount should be allowed to collapse to the point where the V belt cuts an oil cooler line. Stuff like that isn't the cars fault.