The Rycote InVision are by far the better shocks that you linked, but I have used and still own the Windtech shock that you linked above, and it does the job for the price. I ONLY use the Windtech clamp when I run configs other than my DINa/DIN/NOS/ORTF bars and when I need to run PAS
I use the Windtech with my NBob SGC clips and my vark bar, because it has a tighter grip with the base of the vark bar, and I think its meant for 19mm mics, because like I said, it has a much tighter grip on the base of my vark bar, versus my Schoeps a20s shocks, which are meant for 20mm mics/mounts!
I'm in the process of upgrading my a20s shocks to the Rycote InVision 6 shocks. Going to probably buy [1] InVision 6 here really soon and see how I like it (which I'm SURE that I will). Id buy [2] at the same time, but I want to see how they fit in my SMALL LowePro bags and work with the KCY cabling before I go full in and get a second one
Not to mention, the InVision 6 will have a better grip on my vark bars and the DIY PAS bar that I'm in the process of making
So basically, the Windtech and Schoeps a20s shocks will be collecting dust real soon lol
So instead of buying the $20 Windtech shock, and then upgrading to the Rycote InV anyway, IMO you should just save up and buy the InV right off the bat
EDIT: Also, they make a bunch of different InVision shocks, and I'm sure there is one that would hold your small 2.5" mics
I think the InV 3 is just a smaller, and not quite as stiff InV 6, which may work out for your smaller size mics. I'm just using the InV to hold my active bars, since I only run actives, so I'm not sure which InV model you'd want?
It might help us if you told us exactly what mics you're running?
http://www.rycote.com/producttypes/invision-broadcast-film/http://www.rycote.com/producttypes/invision-studio/http://www.rycote.com/producttypes/invision-video/