I'm a first season beginner, so my input should be judged accordingly!
I have gone thru several pairs of boots via REI trying to get a comfortable & proper fit! One speed laced type boot & the rest Boa's.
I settled on the 32 ST's. I like the Boa system myself. I found that they can be WAY over tightened, which is what I was doing (...got plenty of incomplete & bad advice on fit and how to properly strap in)
This point was was touched on briefly in another reply, but I'll add my two cents to elaborate. Concerning loosening. I have not had the cables loosen on their own, but I have found that while I'm Strapping in,.. The bindings tightening down on the boot will sometimes cause "Slack" in the lacing cable. (Getting the bindings where I want them,.. the boots get squeezed a bit tighter than where I have them laced simply for comfort) If I notice this, usually a quick half to 3/4 turn on the nob takes care of it!
I actually have more trouble with my Cartel's binding straps stretching & getting loose during the course of a days riding!
You're only Young Once,.. but you can be Immature FOREVER!