I do lots of SUP and kite races and travel in some remote places so I just bought the ACR one in your second link, it is nice and small and I think is worth paying the extra for. It comes with a little floating pouch that has a belt/strap loop that can be attached to a harness, PFD etc. and you hardly notice it is there.
It also comes with a few extras that I see they have changed from when I got mine, I got the strobe light plus an LED headlamp and waterprooof bag. It now comes with the strobe and a first aid kit.
I have heard of a few occasions where people lost at sea at night have seen search rescue boats near them but haven't been able to get their attention and wished they had had a light so I think this little strobe would be very handy if ever you found yourself in that situation.