IMO the thick and heavy copper slug light engines are any P60 host biggest advantage due to superior heat sinking. Reflector P60s in contrasts has very poor heat sinking by todays high current demand standards. As far as I know my P60vn are the most heavily driven P60 on the market so heat sinking is key.
Among the heavy hitters Quad XPL HI is likely the most reliable high output light engine to date with reasonable heat and performance. P60vn with reflector SBT90.2 is likely the most stressed for obvious reasons. Next up would be the 7X XHP50.2 mule. This light engine is by far the most lumen but you better have a twisty. Most clickies will eventually fail.
I LOVE P60 related lights. I try my best to keep this platform alive.