Nobody here is using them, so we can't really judge. I think that company makes a bunch of stuff for Mustangs, though, so maybe try asking some of those guys about product quality, etc.
Part of the problem is that they are only for the early cars, so that means only for the early struts. That means no BAT Euros or ST200, or even SVT struts. Koni makes a strut for the early type springs, as does Spax, but after that you're into KYB et al.