They’re not lighter than a Bullit, quoted weight for Bottlerockt on Transition website is excluding shock.
Though having just checked the website, it does look like they’ve updated and slimmed the frame down slightly. I know an old one, with coil shock, was 10lb near as. My old Bullit with coil shock was actually only just over 9lb!
Sweet little frames though
EDIT: WOW, the new frame (on Transition’s website) does look like quite an update, two different mounts for the shock (different travel), hydroformed tubes, 16″ seat tube (not 15″) so you can actually pedal the thing if needed and you’re over 5ft8, 31.6 seatpost (so you can run a dropper post), tapered headtube etc… http://www.transitionbikes.com/Bikes_BottleRocket.cfm