I'm not sure if that's a vent on the IQ but the isolation is average for a high-end monitor. It's better than with the K3003 or IE800, though. The IE 800 isolates pretty poorly.
Shure tips fit but my Shure gray flex sleeves (which I normally like) sounded pretty bad. The IQ has way more treble than the UE 900 with the stock tips or with the shure flex sleeves. I found some other tips that work decently well but most just sound bad.
The IE 800 has some strange ringing in the treble, there's a lot of treble energy and slow decay. The treble actually sounds brighter and more splashy than that of my IQ. The bass is heavier with the Sennheiser, but not by much. Soundstaging and clarity are very good - I would say the IE 800 beats the IQ in soundstaging and keeps up with it in clarity.
If I'm going to listen outside all the time (with the traffic noise, people speaking, etc), wouldn't a high end IEM with mediocre isolation defeat the purpose since I won't be able to hear/make out all the details and etc. I own the JVC FX700 and PFE 232