I think the sellers of these "snake oils" rely on the "bit of knowledge" saying... SOME bacteria can survive FREEZING, DRYING, EXTREME HEAT, EXTREME COLD, MASSIVE DOSES OF RADIATION.... and so on.
BUT we are after growing certain types of bacteria, which exist in a narrow band of conditions...
I would like to state that I have NO experience of these additives, and would like to see a "side by side" test done... perhaps a job for a magazine ?
But speaking from experience, and that of many others in this game, there is NO shortcut that will logically work, I have cycled many tanks (mostly the fish in cycle) and have lost a lot of stock, through ignorance and impatience...
I would NEVER do another fish in, experiements I have done, have shown that the tank is FAR healthier when a fishless is done, even long term (3 years so far) my main tank is showing a vast difference to the control tank I setup as "normal" in my eyes.
Plants are feral - almost out of control... so its not only fish that benfit !
You are (hopefully) in this game for years, if not life.... I'm sure 3 months TOPS isnt a big price to pay ? It IS worth the wait...