Looks awesome! But just curious, what is the purpose of a floating rear brake? Im interested to see how well it works out for you!
For argument's sake, I'm not going to discuss carbon fibre brakes. There are three kinds of brake rotors: solid, semi-floating, and full floating. Solid are what one finds as O.E.M. on rear brake, and many cruiser & standard front brakes. They are stamped from a single metal disc and bolt directly to the wheel, and are where the pads grasp. Semi-floating are made from two pieces of metal, an inner piece which bolts to the wheel, often aluminum (Al), and an outer piece of either iron or stainless steel which the pads make contact with. These two sections are connected together via rivets, sometimes incorrectly called buttons - they are in fact, nearly rigid. Full floating also use an inner section with an outer section using buttons to connect them. Semi-floating & full-floating look similar but behave differently.
The positive aspect of solid rotors is they are cheap to produce. But when subjected to high heat loads and/or frequent heat loads with little/no cooling intervals, are subject to warping because they can't expand as easily. To help combat the warping issue solid rotors are thicker (heavier).
Many O.E. front rotors are actually semi-floating (yes, even Italian bikes). The advantage with this type is they are usually quieter than full floating. An advantage that a floating rotor possess is "knockback", where they knock the pad back so that there is less pad drag and heat build up. The rivet used on semi-floating rotor has springs that reside between the rivet and disc components. You should feel some "give" if you move the rotor perpendicular to the rotor, but the rivets usually cannot be spun around. This "stuck" aspect doesn't allow as much heat dissipation as full-floating rotors
Full-floating use buttons without the springs. Instead the buttons are held in place with a snap ring or an e-clip. These buttons allow full float and can be turned completely around with fingers with little effort; they always vibrate/rattle. I always spin the buttons around when ever I wash my bike making a point to spin the buttons while the wheels/rotors are suds upped to remove any debris that could gather in the spaces binding the buttons.
Full-floating rotors have the advantage of expanding in all directions whereas a fixed one can't. Also, solid rear brake rotors don't have the benefit of having the cooling air stream that front brakes do. Again, warping can be a chronic issue.
I have stated that though I may not be en vogue, I do use my rear brake, and have warped my fair share of rear rotors (even O.E. front rotors). FAQ: all WSB, WSS, & Moto GP bikes use full-floating rotors.
Note: The last (#3) picture clearly show the snap ring used to retain button of full-floating rear rotor