I run Ofna JL glowplugs (T5) in both of my JPX .28 and my Picco P7r and I've had great luck with them, actually I haven't had one go bad yet
I'm still running a Picco P6 glowplug in my Clockworks JL (backwards, huh?) and I'm still running the original I put in the engine when I got it (roughly 1 1/2 gal on it). In my standard plug engines I've gone back to the McCoy plugs, they seem to hold up the best of what I've tried (O'donnell, Dynamite, RB, Novarossi). I've been running the MC8 in both my Novarossi N21R and my old Picco P7r Evo 2 (standard plug head button) with great success.