Gonna disagree, but only partially. If the track has areas in which late/threshold brake maneuvers are important, you will be faster with front brakes. But learning to modulate correctly is a whole new skill. Also, most drivers put too much bias on the fronts thus inhibiting turn-in. Fronts are an assist to the rear brakes, not the primary source of stopping power.
I also think fronts are a good idea if you plan to transfer to cars–that heavy almost-all-the-way-though-the-turn trail braking that can be done with a rear-brake only kart doesn’t transfer well to other 4-wheel motorsports.
Finally, a good compromise is the front brake systems with a foot operated rear brake and a front handbrake on the steering wheel. It takes some practice but eventually it becomes almost second nature to add or subtract front brake depending on the needs of the particular turn. I find myself mostly disregarding the handbrake in most turns, but depending on it quite a bit in classic late brakes like a hairpin at the end of a fast straight.
Worth the $1000? Depends on the tracks you’ll be at, your skill level, and how badly you want to gain a few tenths.
