There's nothing wrong with "sublight". In fact, different ships may have different propulsion systems for sublight speeds, so "sublight engines" is probably a good generic term if you're not making a specific engineering reference. BSG muddies the waters a little bit with "FTL", because they use the term of jump drives rather than as a generic category, but I suppose you could use it generically if you wanted to. I'll probably end up using "FTL" as a general category of technologies that allow you to go from one place to another faster than light, but not any specific technology. I'll have separate terms for drive systems that operate on radically different principles (e.g. jump versus warp versus hyperspace).
