I'm sure the Terrain dog tag is very nice, but I'd question going all out on that kind of knife. If I was going to spend that much on a necklace knife, the Rike Cicada is more interesting IMO. They also make the Beetle, which is far cheaper and has a bottle opener.
I do have that Twosun utility blade holder and like it a lot. It fits in a 5th pocket and allows you to bring a knife anywhere and just toss the blade if there's an issue. Plus it's nice to have a utility blade for things like sandpaper that you wouldn't want to use a nice knife for. Personally, I prefer the Twosun TS302 for the sleek design, but the TS149 holds the blade more securely and has a bottle opener.