Then when...even later the Zenith PRO appeared...WITH the "System"...I wondered if there were complaints about the Zlide...
Not that I know of. I have 3 Zlides (one 2ml and two 4 ml) and they are just about perfect. I much prefer the slide/push to fill feature to the twist to fill on the Zenith. Never had any leaking, flooding or gurgling--zilch, nada, zip. Push, fill, close, you're done.
I also prefer the look of the Zlide, but that's totally subjective, of course.
The Zenith had the "Auto Liquid Feed Shut Off System While Refilling"..."For Flooding & Gurgling Prevention"...but when the Zlide later came out without it...I figured they decided it really wasn't needed...
I agree. The Zlide has a silicon plug on top to prevent leaking from the top cap and it works as intended. They also give you an extra plug should the old one get bad. The Zenith doesn't have a plug because the twisting mechanism closes the filling hole tightly.
The "auto liquid feed shut-off system" is a bit of an unnecessary gimmick that never did anything for me (I never use it) and just makes the tank more expensive to manufacture. Even Phil admitted that "it's not perfect" in his video.
INTERESTING...(I've never tried the Zlide)...
This is a personal decision. If you're happy with the Zenith, and you already own a bunch of them, I can't see any compelling reason to switch to Zlide. They both work about the same--for me. I find my Zlides to be a bit more user friendly, though, and less expensive. You can easily take the Zlide apart for cleaning (or replace the glass tank should you break it), it's easier to fill, and doesn't have that metal riser on top, which bothers some users. I don't much care one way or the other, but some of my favorite DTs don't work or look good with the riser.