Having done a bit of work on hours flown, the number of occasions I fuelled with Avgas and allowing that the Permit resets the clock, in an average year it makes no difference to the number of checks I would need! It will bring my mid year check forward, which means I will have the day out in potentially better weather but that is it in my case.
The only extra cost will be the fuel itself, which is about £140 per year extra.
This is based on an MCR (912ULS) with an 80L tank doing 125kn and 80 hours a year. Most flights, excluding my week in France, do not require re-fuel due to 4 hours flight time plus reserve.
I will refrain from commenting on big issue / minor pain, you can make your own mind up!
Rod1