VERY nice shop! You'll love the rotary lift. It's top of the line and you don't have to worry about it falling down while you're under it. Some things you don't want to save money on.
On the 7' door, rather than a major change, consider replacing the sectional with a roll up like this:
The unit rolls up into about 12" diameter. Should fit inside the joists of the loft.
I had 5 sliding 'barn door' type doors on my shop and just replaced them all with these doors from Janus. (Google roll up doors) Mine were made over in Carrollton GA and averaged a couple hundred bucks each...actually cheaper than building a barn door after you consider the material, track, rollers, etc. And they LOCK.
I can put one up by myself in about 2 hours but that is using a forklift to raise it up. Otherwise you'll need a helper. They're not heavy.
A problem with the standard sectional garage door is that, for me at least, the track is exactly the height of my raised hand. I swung at a wasp one time and nearly broke my hand on the end of the track.