I just got home 'bout 10 mins. ago, but updating this mod is the very first thing I did after discovering there'd been a SF release.
The nature of the error was the same as Spartan114 discovered before; GSP missions explicitly require certain of the vanilla variants as opponents, and Alex routinely renames them presumably to follow stricter or more logical conventions, as any good developer will do.
I'm considering copying all variants in the current version named by GSP missions into the mod itself (just the *.variant files, not the hull defs or graphics or any other stuff) so that future variant name changes of this type will not immediately break the mod, but for now the risk remains. I must remain ever vigilant.
Ver. 0.7.2 up fo' d/l.