[NoxNoctum]

I got interested originally in the 700s after hearing that they have very poor isolation (but very good sound). I'm trying to get earbuds/IEMs for work and so I need to be able to hear co-workers etc, so low to non-existent noise isolation is something I want. My question is, do the 700s, 750, 850 all have similar noise isolation? (or lack thereof?) 
 
Also, how do they compare sound-wise? I'm looking for a lush, warmer sound while still as detailed as possible (though a lush tone is more important to me).
 
Oh yeah, one more thing... this may be too niche to get any feedback on, but something that sounds good with black metal is a plus. (this is the main reason a lush sound is what I'm looking for --- some of the more "analytical", bright IEMs I've tried have made this kind of music sound very tinny)
 
Thanks.

 

[WoodyLuvr]

Regarding Isolation
There was no big difference between any of the FX models (FX500/700/650/750/850/1200) that I demoed as they are all vented however, due to their smaller size the 750s were easier to deeply insert into my ears and thus offered in my case a slight edge in isolation. The FX series are definitely not as isolating as my Shure SE535LTS-Js or even SENN IE80s... with that said my first extended listening session with the 750s was on a seven hour plus flight from Bangkok to Cairo and they isolated well enough for air travel for me to use them again... I actually am able to flip them over (cord over ear) and insert them that way.