I've not used either one, but they look to be fairly typical designs.
It's important to understand that with a typical diabolo pellet, the skirt is significantly larger in diameter than the head. Sizers are designed to change the skirt size only.
This can be useful in some circumstances, the effect being of course to keep the skirts truly round and consistent in size. But it's not a panacea, and importantly, NOT a substitute for buying pellets with different head sizes.
IMHO the issue with the old Beeman sizer, a well-made unit similar to these but with interchangeable dies, is that all the dies were too small to work well in a springer. (the biggest die in their .177 set was .180; most .177 barrels measure about .182 across the grooves, so .177 pellet skirts are usually this big, or slightly larger, to seal properly.)
An interesting exception is the TR Robb sizer made in the UK. It uses a tapered bore with a movable internal stop, so that the size is adjustable, but the skirt always remains larger than the head. I don't have one, but it's certainly an interesting idea, and quite popular there.
https://www.trrobb.com/product/adjustable-pellet-sizer-177
IMO, waste of time. Measure and weigh is more empirical.
I found that as long as the pellet heads are large enough to be "sized a bit" when loading into the leade all pellets will start down the tube exactly the same size. I shot unsized CPLs from my .177 HW springers for decades with no issues, however that all changed after buying my .177 HW95 on sale from AOA for $299+shipping. The newer HW95 had a considerably tighter leade than the R9 and I would get a "sore loading finger" after a shooting session due to the tight pellet fit. Here is a pic of new CPLs pushed through the tighter leade HW95 and the looser leade R9. The crisper/deeper HW95 rifling is easily visible.......
Then I made up a few pellet sizers putting out 4.48mm, & 4.52mm pellet heads, plus the skirts were rounded/expanded a bit. Initially I used two pellet head sizes, 4.48mm for the tighter leade HW95 and 4.52mm for the looser leade R9.........
I lapped out the 4.48mm die to put out 4.50mm pellet heads and found that both guns were accurate with 4.50mm size so that's all I use. It only takes 5 seconds to casually size each pellet (about 720 per hour) while "surfing the web" (or whatever).........
As a side note, I tried to size supposedly 4.52mm JSB exacts using my "4.50 die" and found that a LARGE percentage simply dropped past the sizing ring of my die with no sizing at all so I measured a few tins and this was the result...........
A while back I ordered a few tins of 4.52mm Air Arms Domes. Just for grinns I pushed the "tin marked" 4.52mm AA domes through my 4.50mm die and almost all were sized by the sizing ring. I also measured some of the "4.52mm marked" AA domes finding that I got a consistent 4.51mm reading with my digital caliper.........