When I first began shooting, I used to watch the local cops at my club compete in PPC on the club's indoor range. Most all of them used the Safariland competition speedloaders that work just like you describe -- push button, spring-loaded. You had to keep hands OFF the cylinder and simply push the stem of the speedloader for it to work properly, IIRC.
Obviously, the classic, low-cost (and compact) and ultra-durable HKS speedloaders don't work that way -- you must hold the cylinder if you are to be able to twist the knob.
I have never used any speedloaders other than the classic HKS and while I would bet some work faster or easier, it just seems to me that when worked as a whole system of loading, shooting and ejecting... my fingers are through the frame and grasping that cylinder as a matter of course of proper and certain ejecting.
I am not, nor have I ever been "Johnny Tactical" and while I do carry a handgun every single day, my world of handgunning and shooting centers around ENJOYMENT. I do what I enjoy doing and most of the other stuff takes a back seat. And I only bring that up just to say:
it seems to me that those cops back in the day using Safariland competition speedloaders would be quite the "bad training" in today's tactical-EVERYTHING training "mindset." Unless they were also carrying big, tall, bulky, fragile speedloaders on duty.
Heh -- but even in 1988-89 when I was watching them... most of those guys were probably issued 9mm semi-auto pistols anyway. And for sure, nobody worked the mean streets with a K or L-frame sporting a gargantuan barrel and an Aristocrat sight.