For anything substantial, you'd want a bigger model anyway.

For simple tasks, they're already saturated, and you'd prefer the faster model, so that you can have a realtime/interactive-ish experience.

Or to put it bluntly, it's cheaper if you don't value your time. That goes for smaller models in general -- need more handholding, more correcting -- but the Chinese ones are slower on top of that.

As for speed, Sol on Low is faster than Luna on most settings.