NE,
I don't think you are correct but I might misinterpreting your words. So I apologize for that.
But let's consider the facts:
Fact 1. Hydrogen has less BTU than gasoline. Does it make sense to replace gasoline with increasing amounts of hydrogen? No
Fact 2. In small amounts (how small? experimenters reports very small amounts as effective) hydrogen help gasoline to increase the turbulent flame front leading to a better transfer of heat and more useful work.
--> Very small quantity of hydrogen acts as "catalyst" (forgive me for the term, take it as a metaphor) improving the thermal transfer.
If what you're saying is that with the existing manufactured I.C.E. with they closed loop control and mapping it is almost impossible to add an open loop modification that would change the kinetics of the reactions, than I might agree with you.
Said that, on carburated engines the modification might still be viable once that proper tuning is in place.
I too have many pending questions on the safety of on-board hydrogen generators (hydrolysis, plasma reformer, ...). It has been proved for example that hydrolysis using standard stainless steel forms hex-4 CR that is really poisonous...
But the technology might work as advertised.
I just found this that I didn't know about
:
http://www.ronnmotors.com/cms/
They seem to believe in it as well.