During the past 15 years or so I have owned some scopes with dual-speed focusers, one made by William Optics (ZS66SD), one made by Lacerta (an upgrade to my Orion 80ED), one SkyWatcher on my ED100 and a dual-speed focuser on a SkyWatcher 130 mm reflector. While I have found their operation to have some redeeming aspects I haven't exactly been overly impressed; the ones I've owned either had odd mechanical problems; a "spongy" feel when turning the focuser; were distinctly rough or hard to turn; and/or had problems with either slippage or being too tight. I am a visual observer, and since the problems I have encounted with dual speed focusers so far seem to negate the touted advantage of dual-speed focusers for visual use (the easy and vibration-free fine focusing) I have so far stuck with single speed focusers, even to the point that I quickly reverted to the stock single-speed focuser on my old Orion 80 ED.
But I am wondering if I might be missing something because I simply haven't had the chance fo try a truly high quality dual speed focuser. I have read a lot of praise of Starlight FeatherTouch focusers, but I have never had the chance to try one for myself. So I'd appreciate it if you could explain to me what makes them so good that people are willing to spend substantial funds on upgrading their scope's focuser with an FT. Is it only an advantage for astro-photography, or is it also a nice upgrade for visual observers?
Also, I am aware that there are other popular dual-speed focuser upgrades made by Moonlite or Baader's Steeltrack. Any reports on how they compare with FT?
Thanks & Clear Skies,