Pro built/factory built is one of those things that always tickles me, when you see it on a prospective buyers list of wants.
Dont get me wrong, I don't want to run the factory or any other pro down, you are guaranteed a certain quality level and that things will be to a certain standard. (Or that should be the case...)
BUT, what gets forgotten, is that a commercial build, whoever it's by, has to by rights, at the very least break even cost wise, (assuming profit from parts/components sales) and should really make its profit margin however small, that might be. Which means controlling the labour cost and so the builder is limited on time. The nice touches, the extra care and attention, at the detail work, generally have to go out of the window! Well, unless it's one of those very, very rare cases where a buyer will pay to have that level of build carried out.