I know that stout faucets were devised as a means for emulating the cask ale experience but how close are they? Can I skip getting a beer engine at home and just get a stout faucet and beer gas?
I think the 'cask ale experience' from stout comes from the nitrogen in the beer rather than the faucet. The stout faucets that I have seen pour the beer very smooth and slowly, to compensate for the long lasting foam that would otherwise a proper pour impossible.
Beer engines, on the other hand, can have a sparkler to maximize foam from the small amount of CO2 & N2 in the beer. This would be overkill if your beer is carbonated much.
Furthermore, you don't need a beer engine to serve cask ale, it's common to just use gravity. The beer engine is only used when the cask is far from or below the bar.