have both lights. at this point in time, EDC both.
other than the obvious diff. in size, and the diff in UI, both are very nice lights. both plenty bright and with the multiple o.p. levels can have a long burntime.
as far as beam characteristics go, the Bitz i have is just a bit warmer than the Twisty-100-Tw that i have. actually, i should say not as cool as the Twisty, since the Bitz is not really a warm beam, IMO, and so to call it "warmer" as i did might be misleading.
the Twisty has a brighter spot, whereas the Bitz's central spot, running off of a CR123A cell, is less well defined. this, despite the Bitz's higher claimed lumen value on its MAX o.p. level as cp. to the Twisty's claimed MAX lumen value, makes the Bitz to appear just a very little less bright if one is aiming it on an object ~40' away. however, outside the central spot the Bitz appears as bright as the Twisty.
before anyone asks, i have never owned a camera. so, sorry no beamshots or actual in use pics of either light.