I would definately make efforts to fit any type of reflector which uses more than a single flat bent sheet. (technically a cylinder)
Lumenarcs are definately worth the trouble and cost IMO, and its possible the lumenmax is just as good or better. These things are all just cheap/half-assed copys of warehouse box lighting designs, so its not like any brand is copying any other brand really. An optimization is an optimization, in a perfect world, all reflectors would be the same optimized shape for a given application. We encounter comprimises made to ensure adaptability to a wide variety of situations. Example, a reflector made to cover a 3x3 area being used on a 2x3 area, means light will be wasted.
Reflector choice is very application specific, perticularly when you are able SEE the missing convergence points and things which sanjays testing makes appearent to someone with a good grasp of light behavior, but would be quite missleading to someone just seeing the 3D intensity plots as if they were rays of light comming from straight down.