Since they pulled it off the market it must have done something like burn up a few engines.
Remember... Fuel additives are basically snake oil or non functional and I am going to add your beloved SeaFoam into that. Reason I am dissing SeaFoam.. Several years back I shipped a container of used motorcycles to Jamaica from the USA. The dealer I bought them from recommended that we drain the tanks as required by the shipper but make sure the float bowls were full of a mix of SeaFoam and fuel. Well needless to say I had to tear down EVERY bike's carbs and dig the blue corrosion out of all the idle circuit jets... And that was only after 5 weeks of not being run.
On your 4 power stuff-- Look at this website
http://www.empowernetwork.com/timothy66/blog/do-fuel-additives-really-work/ If it does what they say it will do... The forst thing I see happening is that any varnish or sludge in the system is going to get broken down and suspended in your fuel to clog up your filters and or injectors, carb or what have you. So after reading this it seems logical to me that they would have to pull it off the market for that reason alone. Sort of like what happens when you take an older diesel and switch it to BioDiesel. All the sludge and varnish suspend and you go through a bunch of fuel filters for the first couple weeks you use it. Don't ask.