That one you linked to looks like a quadlock clone... the quadlock attachment to the bike is very clean.. you can ziptie it or use the rubber band things.. I've been using the rubber bands and have no doubt that it's secure (I've got the phone attached to the stem)..
the good thing about either of those designs is that the phone can stay in it's "bike" case all the time.. I keep mine in that quadlock case all the time.. and it's really easy to take the phone off the bike and use the camera or answer the phone or do whatever...
I also use the wahoo rflkt+ but before I got that I wasn't that worried about heat.. (at least while the phone isn't in the poncho) you'll get more heat from sun if it's sunny outside anyway
... even though you didn't ask, the rflkt+ is GREAT.. I lose maybe 5% of battery life an hour.. and I haven't had any connectivity issues with it... (I just use the cyclometer app and road ID when I'm riding and make sure nothing else that would use sensors and stuff can run in the background)