Here's my two cents:
A performance variator will not help you with your launch.
One of my two Hobbit does have stiffer clutch springs, and yes, the "launch" is certainly "harder". The clutch springs do not engage until a much higher RPM, and the clutch, when it does engage, does not engage smoothly, but rather hard. The engine revs are up and when the clutch engages, the revs drop rather abruptly. I've heard others say that it almost caused them to wheeley (sp?), it was so abrupt.
Ideally, the clutch would "slide" or "slip" until your moved from a stop and coming up to speed, but it doesn't work that way. Think of driving a manual car with a "tall" rear axle ratio - you rev it up and drop the clutch - it's kind of like that. You get off of the line quicker, but the clutch, once engage, still has to "fight" against the tall rear axle ratio.
Is that bad? No, I don't think so - I think it is a preferential thing. Both my Hobbits have Leo Vince exhausts (both 50cc, one ported one stock porting), and the power band on both is higher than stock. That, combined with so many hills in my town, and the fact that the speed limit in town is 30 MPH (or less), combines to mean that I'd rather enjoy 0 to 30 MPH acceleration than have top-end speed. Given that set of facts, I'd rather have the stiffer springs on both of my Hobbits. I'd already have another set now, but my original source (Treats on ebay) told me that he did not have any more.
Also, a different variator is not necessary to help you with acceleration. If you haven't done so, just replace your variator weights with a lighter set. It will help immensely with your 10 to 25 MPH acceleration. There's some info in the Wiki on this topic.