Never used those, but have used quite a few of these wirefy butt connectors and other wirefy connectors. Sanded the insert of one down and it was at least copper colored They offer assorted kits if you need a few of each kind too.
I'm getting ready to rewire my dc panel, so I thought it would be a good to to test the ones I purchesed from Amazon a while ago (different than the ones you've posted, but still purchased to save over anchor connectors). I ran out of weight before it broke. 160 lbs on the ring in the picture. I used the DIY crimpers from Main Sail's site with the heat shrink Jaws.
I initially did not like Main Sail's crimpers. It doesn't feel as solid as my set from Anchor. Using the same crimp connector with both set of crimpers, the Anchor failed at less than 25 lbs (12.5 since it was looped).
I've used the adhesive lined heat shrink connectors for decades. Never had a corrosion problem in a joint using these. You'll see the whitish adhesive ooze out the end when you heat them and bond to the wire insulation forming a moisture proof seal.