To those that have scratch built - would you do it again?

I haven't built one, but from the people who've built them here, I'd consider it for a flatbed especially.

I think the only really hard part is adding a slide or two, so assuming you don't want those, I think it's a good option. I know that most TC manufacturers have done a lot of slide design/redesigns, so I'm assuming that's pretty difficult to get right.

If you haven't taken a look at some of the designs here, look for those threads.