I had the same experience as MarkTwain, I purchased the Roxanne before I tried the Noble lineup, I thought it would be a good matchup and from the review I have read on Head-Fi, i was ready to be amazed as some describe Noble as better mid/treble than JH and with same punchy bass along with wider soundstage.
The moment I put on Noble (K10U first than Katana), it was a relief. I can understand why some would describe Noble having better mid/treble, it does have the same/similar extension like the Layla, but the mid/bass is not there. It's not dynamic/lively to listen to, and because of the lack of mid/bass, it does gives the impression of having a wider soundstage.
That's not a sound signature I personally enjoy, and it does come down to taste and the music you are listening to, but to me, K10U and Katana are no match to my Roxanne, and certainly not to Layla. I thought the difference between Noble and JH would be much smaller, but it turns out to be quite different in sound signature. I would also point out this, there are many other cheaper earphone that has similar sound signature as Noble lineup, I can't really justify the price they are charging. I even tested some Chinese brand earphone during CanJam, and some sounded very very similar to Noble. On the other hand, there are no earphone that sounded like Roxanne at least to my ear.
Noble does have the biggest stand during CanJam London, they are fantastic on marketing, and their shell customization and artworks are amazing. I would however rather spend my money on sound i like than the appearance of my earphone. At the end of the day, I walked away from CanJam pretty happy, Layla is an upgrade to my custom Roxanne, but not something I can afford at this point, and I hope something better/cheaper would come along when I am thinking of upgrading again, but for now, Roxanne will do.