A Shakti to the wallet I'd say, and a placebo effect at the most and they don't even look pretty.
An autoformer can lend a tube like sound to a solid state amp. This can and will make an amp smoother and less detailed like all but the best tube amps. After all sending a signal through hundreds of feet of wire is not going to increase detail. The sound derived is not necessarily a bad thing but a matter of preference.
