My opinion only, but wouldn’t think you’d see much of an increase. Been racing shifters for years, but recently went into Rotax due to entry numbers. I’m learning quickly, any issue with a Rotax motor can be very costly. I’ve found if you maintain your shifter motor and treat it right – it will run dependably for a long time. I suppose the same is also true of the Rotax. On top of that, the ability to fix a shifter motor using your own labor (relatively inexpensively in comparrison to Rotax) without having to send it out for repairs is a cost savings in itself. Honda parts in general are about half the cost of Rotax.
I find that the tire wear on the Rotax to be very similar to that of the Shifter – after all, I don’t think you are going through corners and such any faster on a shifter. Biggest change in the shifter will be the harder braking zones, acceleration and constant pull through the gears. Typically I can get through 2 or three race weekends with a set of MG yellows. That’s about what I’m seeing on the Rotax with D2’s.
And yes, practice your starts. Not neccessarily to get the hole shot, but to not get run over if you stall it. Not a good thing when the rest of the pack is attempting to avoid a stalled kart on the line – and yea, it’ll happen, happens to everyone at one time or another.
We may not be the fastest on the track...but we're having the most fun!