I have both of the species and I'm a big fan of asian tarantulas but honestly, I would trade metallica for C. cyaneopubescenes any day. Just make sure to also get something else because metallica cost double
Pfft, I'll give you a b. Vagans, and an A. Hentzi for the p. Metallica
Kidding aside, if you like the GBB more, or are more comfortable with the GBB rather than a p. Metallica, go for it. "Value" is all about market, if it's just for your personal collection and that's what you want, go for it.