After mine tried to kill Brian Kendrick when a Slick with 10 hours on it and one with just under 200 hours on it, left him with only 3 cylinders running, total, on 1 mag, he managed to get Lycoming to spring for the SureFly’s since the OH was still in warranty. To set it up, you have to run one mag off each battery and the batteries have to be independent of each other entirely. Took about 20 hours of labor to set it up. The backup for one mag battery is the other mag hooked to the other battery.
It’s definitely a pricey switch for a pair, and honestly, if Lycoming wasn’t buying them, I’d probably gone with your setup. But after 3 Slicks cratered in 200 hours on a Factory OH, I don’t miss them at all.
They are most noticeable on cold starts and climb performance. My CHT’s in climb are 20-30° cooler. Heavy, I can climb at 120k/700 fpm into the mid teens at 1/2 Cowl Flaps under 380°, used to be 390+, full open. Running a little cooler in cruise as well.