This is a guest review of the K&T T-Rex CNC Head courtesy of Tanasit.

First a picture of this head fully assembled on Tanasit's T-Rex. This is at the time of writing the only CNC head available for the T-Rex but more examples will be arriving very very shortly.
Fitting this head to the T-Rex is not a simple bolt it on operation, some modification of parts is required in order to get a good fit. Firstly the feathering spindle and dampeners is slightly different to stock, a picture of the dampers fitted to the head is below. Secondly the flybar mixer hub when secured by the screws to the CNC rotor hub causes some fouling of the hub mounting screws on the mixer arms. Also below are pictures of the affected parts and the slight modifications required to avoid this problem. The areas that bind have been marked in red for easy identification.
In order to use this head succesfully with the MicroHeli washout arms some further modifictaion was required, this may not be entirely necessary for the stock washout hub. The problem is alignment of the antirotation pins with the holes in the MicroHeli washout base. Some material needed to be removed from the collar locking ring for the CNC head in order to get perfect alignment. Pictures of the collar and it's modifictaion are shown below. Basically some material has been removed at the gap in the collar locking ring in order to get a tighter fit onto the main shaft.
The modification in Tanasit's own words :

The collar with the 2 pins that required some modifications in order to fit on to either the stock plastic guide or the aluminum guide:
 
1.  Open up the gap by filing the material off the opening.
2.  File flat the outside surface of both pins. you can see this from the first picture.
3.  Enlarge the guide's holes outward.
4.  Remove some material from the inner wall of the collar so that it can be clamped closer onto the metal head.
 
You may be able to do only the first 3 steps but if you do all four, you will get a better clearance. Note, if you overdo this the pins will have too much play within the holes, therefore you may want to grease the pins to prevent "metal to metal" contact that will cause radio interference.
So is it worth doing this upgrade, well Tanasit has these thoughts on the subject :

Whether it's worth doing so?  It depends on how handy you are when working with small objects that require precision handling.  For me, I had blades tracking problem that I couldn't live with so I had to find the way to fix it and this seems to be a resolution because after I logged more than 10 flights, the tracking is still on spot. Since I am using the CF blades which is about 20 grams, the head stiffness that I set works just fine.  Forward flight has no pitch up/down tendency and my trex grooves very well.  Hovering is somewhat sensitive thus requires a very gentle input or the machine will look jumpy.  The cyclic controls are powerful at the head speed I run, so mild 3D can be accomplishe just by 80% of the available throw on both aieleron and elevation. Other flyers may want to try the new Align head with 4 o-rings and see if they are happy with that setup.  As for the binding of the mixers' arms with the hub mounting screws' head, I replaced the stock mixer arms with the Flight Tech CNC ones that come in 6 colors

These arms are very thin and will easily clear the hub screw, but there was a slight problem with fitting: the inner ring of the included bearings is lower than the outer ring, so when the arm is screwed down tight, the outer ring with touch the hub and get stuck!  To fix that, I had to cut the stock brass sleeve in half and use them as the washer so that the inner ring will come in contact with the hub.

My thanks to Tanasit for the pictures and words.