I think these are great. They feel well machined and stable. I've previously used Sperzels which I find unstable and pretty roughly machined, and now Gotoh 510s which are incredibly smooth and probably my favourite. So on that scale I'd say that these are definitely better than the Sperzels by a long shot, but can't really match the sheer brilliance of the 510s.
Essentially I would use these as my go-to standard tuner for good stability and accuracy without wanting to blow out my budget. They're really dependable and solid and that's what I need from a good set of tuners. They appear to hold tuning stability well, even with extended range guitars, I've just opted to have the Sperzels on my Daemoness changed for a set of these.