Took possession of a new pair of IE80s today. Not very impressed, I hope it's just because the stock tips are all dreadful. I'll get some complys on it when I get back to my place as I'm currently at my parents for Chinese New Year.
Midrange is too laid back with too much bass bleed. Cable feels cheap and tacky. Soundstage is ok, but in no way compares to a fullsize headphone(except something like the M50 or KNS8400). Treble is quite nice, however "quite nice" treble isn't really a shining recommendation for the IE80. I'll give it some more head time over the next week before deciding if I'll keep it or try and trade it for something else.
The IE80 never really impressed me. I can think of plenty of similarly priced or less expensive IEMs that I'd rather listen to personally. The IE800 on the other hand is another story: EQ the bass down a bit and it gives most universal IEMs a run for their money.
As for comparing soundstage on IEMs to fullsized headphones: some IEMs have a distinct "out-of-head" sound like the EX1000, but really I find IEMs have a distinct presentation in a lot of cases compared to their fullsized counterparts. I call it inner depth. Kiteki used to talk about it a lot, too. For me, overall soundstage size is less important than spatial cues and the dynamics that go on inside that space. In this respect I think certain IEMs actually outperform a lot of headphones out there.