Are you planning on using nitrogen and a Stout faucet, or are you just looking for a tap with a restrictor plate. IMO, the second option is pretty much useless. All it really does is knock out a bunch of C02. A stout faucet with Nitrogen or beer gas is good if you are looking to serve a Guiness like pint. I really just leave them both alone and carbonate more or less according to the style.
If you were to end up with a creamer faucet, I'd say you wouldn't want to serve 90% of beers through it. I think any American style save stouts would be out. Belgians definately out (most of them need high levels of carbonation). Most English styles would be OK through it. If you brew a lot of English ales, it might be worth considering.