I have been using two of their systems on fermenters for more than a year now. I can easily control fermentation temps down to lager temps in my house at 75 degrees in the summer. You do need to insulate your fermenter with an old blanket or a couple towels. I use a small Styrofoam cooler with about a gallon of water in it and I change a 2 liter ice jug once per day for Ales and twice per day for lagers. I was surprised how quickly I could cool my wort initially. I was able to achieve 10 degrees per hour or more with a small fountain pump in the cooler.
I've been using the ballandkeg unit for a while and it is way more responsive than I thought it would be. I could get 10 degrees or more per hour cooling when I initially turned on my pump. I usually cool my wort to 80 or 90 degrees with a wort chiller in the summer and then use this to finish it up. I'm typically pitching yeast in an hour or so. I can't comment on the Morebeer unit but it does look like it would have less surface area exposed to the wort based on the design.
Here is a pic of my set-up. I removed the towel I use for insulation so you can see it. I happen to be doing a lager with 34/70 so I'm running at 63 F right now. It was set at 58 F the first week and I raised it to 63 this weekend. I can easily do lagers down to the low 50's if needed. The loop is in my Fermonster and the temp probe for my Inkbird (on wall) is down in the thermowell. I've had no issues with sealing the system, but the silicone stopper needs to be dry and the lid surface needs to be dry. My cooler has a few inches of water and a frozen water jug in there. I use an 80 gph fountain pump (approx $12 at Home depot) and it is plenty. A larger pump would only move the water (or glycol) through the pump faster and that would not improve energy transfer IMO.
With good insulation I was able to get down to the mid 40's F with Ice jugs which is a delta T of roughly 12 degrees. I have not tried glycol or any other cooling medium. In theory it should work as the delta T should be fairly consistent in a well insulated system. If I had to guess, you'd need cooling liquid 15 degrees cooler than you want to go.
