Well, the question is whether it'll introduce a failure point... plain and simple, yes it will.
Will it fail? I have no clue, have never used one, and have never even seen one in person.
If introducing a possible failure point into your system is of concern for you, there are other options for drymouth...
First, hydrate hydrate hydrate. If you wear a drysuit, install a p-valve. If you wear a wetsuit, join the ranks of us who readily exclaim "we pee in our wetsuits!!"
Second, can also carry fresh water with you in a camel-back type of rig and have a sip while you dive. This is especially popular with divers who do long dives such as extended cave or technical dives. One example of a hydration bladder is here:
https://www.deepseasupply.com/index.php?product=55
Third, how hard are you working underwater? Mastering buoyancy and especially trim can greatly decrease the effort you use while diving and will dramatically increase your comfort... you may find your dry-mouth is somewhat helped by generally being more comfortable.
That's my 2psi.