"He who marches out of step hears another drum." ~ Ken Kesey
I hate having to turn on the IR flash for the manual in the summer, so much so that we run small jobs on the auto or work hard to do 1 hit prints on the manual. I've heard a different rep. who mentioned that in many cases IR can be more energy efficient than quartz, but not faster.....Very interested in you FF poly white Alan, care to share? Our old go-to seems to have gone to crap in recent batches.
Like Allen said it's the bulb wave length, reflectors and bulb spacing that affects how powerful the flash is. Ours usually burn out before a noticeable difference. If the unit has a power intensity adjustment that could be at fault. Some brand X units randomly will switch from 100% to 50%.