Unless it was multi-sampled with left *and* right hand/foot hits, it won't be worth it to go for BFD over DFHS/DFHS2.
Just to clarify...what are "metal drums"? I know I have a preference in what a drummer "should" use, and I know what I've worked with in the past with the best/easiest results, but I didn't know there were actually drums made just for metal. Because I was under the impression that really any drumset could work for any type of music, tune them correctly, put the proper heads on them, and a drummer that knows how to use them, and sizes of the drums permitting, any drumset (theoretically) could work for metal. With sample replacement, and production techniques, I don't see a problem. I know there are drumsets that are *typically* used for metal, brands, sizes, etc. But nobody sells their drums as "3L173 M374L DRUMZ", they may have a suggestion for what they geared a particular set for (jazz, rock, etc.), but it's never definitive and it's *never* absolute. I have heard clips of people using the same exact kit in DFHS for jazz, metal, rock, blues, country, and pop...it sounded good for all of those styles. The same kit. It's all in how you use the kit.
Sorry, I just had that thought when I read your post, Tornio.
~e.a