Re: Sound Formula/Signature question
They will not sound very similar. SFs are a little brighter than sigs, and the dark crisp hats will sound drier (per the name), than SF med. heavy hats. I have both sigs and SFs, and for crashes they can sound quite close, which is apparently the reason Paiste dropped the SF line, but with hats the distinctions between pairings can add up quickly.
To be fair, I've only heard the dark crisp hats. And I've only owned Sig hats, but have heard enough SF hats to make an aural comparison of overall characters. If it were me, for the music I play (fusion), I'd get the SF hats.