COBRAJET-
Haven't been there in a few years but used to make those trips a lot in a Toyota 4x4 truck and then in an Isuzu Trooper. Both routes, either Cinnamon Pass or Engineer, are really beautiful. We usually made the runs from Lake City while staying there, one way to Silverton and the other that comes out a few miles from Ouray. Sometimes we went over one way, spent some of the day in Silverton and returned the other way. It is definitely a full day if you do that.
The roads vary from year to year depending on the weather and how much maintenance they have had. They get more care now than in the past due to tourist trade, jeep rentals, etc. Probably, the best bet is to ask the locals.
Some of the switchbacks are really sharp and you may have to make a couple of stabs at them in a large truck. The roads are definitely 4WD road, but if you take your time and watch the ruts and rocks you will be fine, just don't get in a hurry!
I haven't had the Dodge 4x4 there yet, but the next time I go, it will definitely go over those roads. Like I said before, I always ask the locals (not the ones that rent jeeps) about the road conditions. These routes are maybe the most beautiful 4x4 roads I have ever seen, hope you enjoy them and I hope this helped. Be sure and take your camera!
Dave