We had a modular built by Nationwide Custom Homes, moved in November 2007. Their closest factory to us is in Siler City, and we got to tour it and see out home in process. Pretty cool.
When we priced it, the modular came out cheaper than higher-end builders we talked to. We had a lot of flexibilty with options, changes, and design. We have several angled walls, not all rectangles. But to what Rich said - there are *some* things they can't do. Where the pieces meet (the "seam" down the middle) is called the marriage wall, and door casings on that wall are thicker than normal because that wall is thicker. And there is a limit to where and how rooms can extend across that wall, since it's a supporting structure. But that did not limit anything we wanted to do, other than being unable to put a pocket door on the closet in our bedroom (can't do a pocket door in the marriage wall).
Nationwide has a model home center on I-40 near Rock Creek Dairy Road - this is just east of Greensboro, way before Burlington. I think you get to it by exit 135 or 138. Anyway - the big white model house with dormers - we built a modified version of that. Build on a different floorplan to cut down the square footage a little to bring down the cost. I also got a full drive-in basement/garage.
One main reason we went with modular because it was faster. They set our house on the foundation on like 08/09/2007 and we moved in 11/01/2007. I think they started grading in June, and if there hadn't been a mix up with the county permits, we would have closed earlier (house was done in factory but had to wait to be set until permits were fixed). We were living with my in-laws, so wanted to get the hell out of there ASAP. Also, we were building near my in-laws, so I couldn't have my jack-ass father in law going over during a stick built process and screwing with the workers all the time.
Another reason, when I look back now, is that you get most of the stuff done in the factory under more controlled conditions. I'm not talking about just weather (which is a big one), but also supplies, sub-contractors, etc. Based on just the limited amount of subs we had to deal with, I'm glad we didn't have more to deal with.
The house did get some sheetrock cracks from the move and setting on the foundation. There is a 1-year warranty - they fixed all the initial cracks, and we'll be calling them back to do any more before November (only have some seams gaping at molding, no cracks). I don't know if this settling is worse than a stick built house. I have no frame of reference. I do know that our old stick-built house, built in 1966, still had sheetrock cracks when we lived there a few years ago.
They did make some mistakes, but the fixed them all. I would imagine this could happen with a stick built house too.
My recommendation whoever and whatever you go with is always to ask for what you want, even if they don't like it, or don't want to build it that way. It's their job to give you what you want, and you're paying for it. Our first salesperson was great with the design of our house, but then she left. The second guy would have refused to do for us what she did - would have told us it couldn't be done. We got lucky I guess that the design was basically complete before we had to work with him.
Oh - also, check with the builder on optional brands of HVAC equipment. I was told by an HVAC friend that what we got is the "low end brand that all contractors use" - not terrible, but there's better (longer lasting) stuff out there. I didn't even think about getting a better brand there.
I wonder if Rockcity did the crane work on my house?
I thought the crane was from somewhere near Greensboro, but I can't remember.