I have an adidas which I find a bit too low-cushioned. (Djokovic bright blue shoe). I simply replaced the insole with some gell replacement from a local store, and it has been terrific -- as far as feel and cushioning is concerned.
However, that Djokovic shoe had ventilation though the bottom, and original insole was mostly perforated. My new Gell blocked all that, and made the shoe considerably hotter.
I cannot feel it now (36°F outside), but I know when the summer comes it will not be ideal.
I also tried Superfeet before -- in other shoes -- but could not tell the difference between them and the original insoles.