If the LHT had horizontal dropouts, I would have bought something else.

I've had both. Horizontal dropouts mean, at least for me, removing the panniers so I can balance the bike (awkwardly) between my knees as I straddle the rack, trying (usually futilely) to get the stupid wheel to line up straight. Get it straight, close the QR, discover that it moved. Open the QR, tweak it, close the QR, it moved again. And so on. Are you better than I am at getting your wheel perfectly straight? Probably - but it's not what I want to deal with on my commute, or when I'm loaded for bear on a tour.

The only reason you'd want horizontal dropouts is to run FG - with an IGH or a SS, you can always run a tensioner. If you want to run FG, you'd better knock an extra 12.5mm off your crank length, since that's the amount of additonal bottom bracket drop the LHT has over the CC, so it's the amount you'd have to remove to get back all the clearance. A fixed LHT would be foolish - not only would it be dangerous because of the cranks hitting, but it defeats the entire purpose of the bike.

If you want something to go fixed with, get a steel frame from 1988, or go buy a CC or one of the other appropriate Surly frames. But leave my LHT alone.