AD + Prismatic might still yield better overall results considering what you can possibly gain in dps by not having to gear for as much mit. Or even the possibility of being able to gear with enough mit while using Prismatic to not need BM anymore for RD and instead go with Force Weapon. I haven't really delved too deeply into that area, though, because I'd need a helm and gloves like what Melkor has for his AM setup to pull it off I think.
At my gear level I have to use prismatic to break even against RD, and BM. Eventually I'd like to switch to Electrify or pinpoint.
I think ultimately GC+PP+electrify would be the ideal situation, but that requires either a lot of mitigation or the acceptance that RD will hurt bad. For AM Electrify should add about 5% dps (not 7.5% like I said previously), on top of your already high multiplier, whereas force weapon only adds 5% to your already large additive buff, so with AD it's only about 2.5% dps gain over BM. I just find it very hard to drop BM because of the huge survivabilty boost it gives.