I don't know for sure, but I think buprenorphine would actually have a higher affinity than naltrexone. In theory, it seems possible that you could be on naltrexone and suboxone at the same time without withdrawals, because the bupe would out compete the naltrexone - does anyone know this for sure? If that was the case though, there would be no point taking naltrexone at all. My bupe doc has also said I can't be on naltrexone and sub at the same time though.
I was researching this topic recently, there have been studies which determined using naltrexone during a bupe taper had a better long-term outcome for relapse rates. I read many times that "in theory" if you have naltrexone in your system, buprenorphine should have a higher affinity, however they will continue to "fight" for lack of a better word, for the receptors, causing minor discomfort. I wish I hadn't had as much valium because I did research this recently.
Baclofen worked for me too when I was serious about cutting back on my alcohol intake. Doctors are happy to prescribe it too, even though it's a GABA agonist, it's not a GABA-a (?) which is what gives us the pleasurable effects, it's a GABA-b (?) agonist which just has the muscle relaxing properties with no pleasure. However footsy, please be aware that the withdrawals are just as bad as any other GABA agonist. I was once away from home for a couple of days and forgot to take my baclofen with me - not thinking much about it at the time - later during the day, I started to get a terrible headache, my whole body started aching, I couldn't eat and my mate told me I looked like I was dying. I seriously could barely do anything, it was very unpleasant. After that episode I decided to taper down quickly and get off it as soon as I could. My doctor never mentioned this to me, but after a little research on the 'net, I learned that it's very similar dependance and withdrawal wise to benzo's. Be careful.