Performance and opinion are 2 different things if one understands the way the halogen reflector and a burning halogen filament work together vs how a halogen reflector and a LED drop in bulb that does not emit the same arc range in that reflector.
My opinion may or may not be the same as others, but when performance is noticeably different/diminished, that was enough for me.
Again, I'm not arguing "what's meant to be in the OE reflector housing." If they experience better performance and feel it's worth their investment than the "understanding of how a halogen reflector works and arc ranges" is erroneous. I'm sure what you are saying is correct, but I'm just playing devil's advocate that maybe those doing this upgrade don't care that it's not "right"....or even know...or care.
Now I'm curious as to what your experience is. Are you saying you have tried an LED drop in bulb and found that light output/performance was worse than a standard halogen bulb? What bulbs and what didn't you like/not like about them?
Keep in mind, I have no skin in this game. I don't have LEDs and don't have an opinion either way. I'm running the OE halogens and just trying to do some research. I want to understand if people who like them are actually right or if the "principles of halogen projectors" that you and others are discussing truly make an LED bulb worthless (even when people say they like them).
Forums are full of contradictory information on a lot of things based on experiences of some, opinions of another, and some people that try to make things way more complicated than they need to be. It's amazing how one person can say something and automatically that part is the best of the best or the worst of the worst. Sometimes until you try it yourself, you'll go nuts.