First hand experience with my 1970 Amazon has taught me that good quality items are a huge improvement over standard incandescent lamps. But the same is true for an upgrade of a low quality H4 unit to a high quality H4 unit.

I used to have Cibié H4 units with the same bulbous glass as a standard incandescent unit would have had (normally H4 units have flat glass). Thanks to corrosion of the reflector I had to replace them. I chose Volvo items (made by Bosch) and the increase in light output (with the same H4-bulbs!) was enormous. Also, the way the light was spread was as it was supposed to be for an H4 unit: horizontal line with a kink upwards to the right. The units that were replaced weren't nearly that good. Most of the light was diffused instead of bundled and directed at the road-surface instead of blinding oncoming traffic.

Then I decided to change the wiring to heavy gauge and a relay and now I have more light than most modern cars! So imaginary improvement...I think not!

daily driver 131
1970 Amazon
The Netherlands