Barbiturate site ligands (agonists, obviously) that don't antagonize AMPA receptors can still be pretty toxic in overdose, just as barbs are, I take chlormethiazole, a barb site GABAergic that doesn't have the glutamatergic antagonistic effects of the barbs. Of those, I've experience only with pheno, and with barbital itself. Pheno is crap, barbital itself is actually pretty good stuff IMO, as long as one doesn't fuck up with it of course. As for differences between the two, I found barbital ot produce a LOT of 'brain fog' whilst taking it, whilst with chlormethiazole it's both a hefty, heavy duty wall-banger of an oldschool GABAergic depressant, a fossil from a bygone age that somehow, miraculously survived the mass extinctions inflicted on most of the oldschool depressants. The ones that were too good for the liking of those who loathe people seeking pleasure. Chlormethiazole, is really clean, clearheaded. Not too long acting, about 5-6 hours, so it won't build up and cause an OD due to a massive half life in the case of drugs excreted as slowly as some of the long-acting barbiturates after someone's been on it a while, takes their normal dose, and ODs because there is still a lot of the drug in their system, etc.