Max Nozin , as you demand proof, and independence, this blog article is from people that made their truly independent replication (Benchtop underwater plasma arc reactor, built using a transparent filter case) and found the production of this kind of gas to have a COP of 1,75 , with regards to the electric energy used To create the gas and the heat energy that could be obtained by burning such gas. Santilli claims 2.8 and up to 7.5 depending on the liquid being submitted to the process and the pressure at which the chamber operates. But these guys from blaze labs obtaining 1.75 with a very simple set up, is not bad. Also they did not consider in this calculation the heat evolved by the process itself (dissipated in the water) nor the light output. Considering those two outputs would increase their COP to some extent.
It is not “something from nothing” is simply getting the extra energy from the matter itself.
There are a number of similar experiments also on JL Naudin's website http://jlnlabs.online.fr/bingofuel/
Whether the heat energy content of the gases (when combusted in air) will be substantially larger than that of the electricity put into producing them will depend on the process used, I guess.