i don't know about the l/g because i don't have lust; but sparks can fly l/s is definitely nothing like rubia l/s, imo. sparks can fly l/s is darker. and soft &slow l/g is pretty much the gloss version of sparks can fly.
Sweet and Slow is close to Damzel, La La Libertine and All Woman. Lust is a cream, and S&S is a frost. Rubia and Sparks Can Fly do not look alike. Rubia looks like a more pigmented Barely lit, though!
Rubia (lustre) is very sheer on me. Sparks Can Fly (frost) is much more pigmented. Just by the nature of the formulas, most will get a more intense colour payoff from Sparks Can Fly.