I just picked up the T1's recently and use the WA7 Fireflies and it's a really nice combo. The best Sennheiser I've owned is the HD600 and the T1 by far is more in my wheel house far as both of those go. I also have a pair of Hifiman HE-500's that articulate certain live acoustic music, chamber music and live Jazz more to my likings that the T1's. Sometimes I go for the Grado PS500's, it just really depends on the genre and mood. I'm sure the HD800s are the cat's meow but for me I love the comfort, size, look and sound of the T1's for orchestral music and other genre recordings that have micro detail and large soundstage. Far as portable I have the first generation DT1350 and those have the Beyerdynamic Tesla sound (not exactly T1 sound but amazing for on ear mobile) and have crazy sound isolation which is what I need in the office.
That's the beauty of headphones and all the brands, such a subjective thing to debate, but at least we have a lot of great options these days to suite our personal needs.