I'm also a big fan of myHTPC, and wish for integration between myHTPC and MC9.0.
Hairstyle, at the moment, is mostly a proof of concept. It is fairly rigid (mainly, it is not possible to customise the menus to remove, add or reorganize the options), closed (can't be used to launch other programs), and doesn't let you use the pictures for anything. Even the 'XML' tags to tweak the look are fairly limited (I tried to make it look like myHTPC but couldn't get very close...)
I'm sure you'll be able to improve HS and make it a great feature. I also understand that it's not your top priority (frankly, though, I would be very happier with tight integration with myHTPC, as this product is shaping up very nicely, with advanced features such as an EPG, which I haven't seen yet on the MC side)
In the short term, I would like you to reinstate the 'Start in hairstyle' option. Currently, if you start in full screen, in TV mode, you get a black screen, which is less than ideal... having hairstyle show up instead would be nice.