Paul, and all in on this one...
Believe it or not, I've had great service from possibly the least expensive plugs available. Swanson's Fireball hot range plugs, both idle bar and open, do well on the medium-high RPM mode many of us use nowadays.
Yes, they had a reputation for blowing the seals a while back, but the uses where this came up were racing and combat. MUCH higher plug load conditions than stunt. And, being inexpensive, it is much easier to pull a plug and chuck it if there's any question about how it looks.
Sure, high priced plugs - OS #3 or certain ENYAs - may do as well, and for a longer time, but where I am, they are not all that available. Fireballs are easily found, at good prices.
(FYI: Swanson is one of the oldest glow plug manufacturers, and still makes them here in the USA.)