Don't spend the money on a slipper clutch, yet. Get good with the one you have. Timing and practice is all you need (don't we all). I had the same problem at Laguna Seca this year, not downshifting correctly. Trying to go through too many gears down at one time without getting the engine up to speed to match the wheel speed. Hence your hopping around? Try going slow to go fast. Keith and my instructor worked (tirelessly) to get my timing down. Roll off, brake, clutch, downshift/blip (hard to get the rpm's up), catch the rpm's on the downside as you let the clutch out, and viola', there you have it. Okay, don't let off the brake or move it closer/farther away, keep you turn pt in sight, set the right speed for the turn, get your steering input correct to set the angle, get you body position set before all this, etc... School is better than a slipper clutch anyday. Sitting on the bike on a stand, doing it over and over, listening to the engine and feeling what it's like helps. Doing it slowly at first to get the timing down really helps when the speed goes up and you need it. I'm still screwing it up (ala the last track day) but keep working to get it right. When you do it, it's sweet and you wonder what the big deal was. When you don't , you immediatly get into a SR and know what the big deal is. It'll come. Just keep after it.