They will be addictive and the "antidote" will be shorter acting than the actual Benzo-esque substance meaning that even if it's taken it'll wear off and you'll be under the influence again.
I saw that on a Horizon program where a friend of Mr. Nutt tried it out (think it was Pagoclone) and the BZD antagonist wore off quite quickly and he ended up being fucked up again.
Still, if it ever comes into use then I'd be well up for going to pubs again
To be sure, there are anxioselective benzo-like compounds that have a higher affinity at GABA-A alpha X (1 through 6) than diazepam. For instance, Imidazenil (IIRC). Some of these have half-lives comparable or in excess of diazepam. So it is possible to have an antidote with a therapeutic half-life and a favorable side-effect profile.