I played a lot around hot ends lately, and even though my "banana" bushing blocks help tremendously (no need to remove the rods, pulleys nor recalibrate), the stock head mount is still very annoying to swap because you need to remove the X/Y small bars.
The remaning of the time I am usually using my alternate butterfly mount: http://www.thingiverse.com/thing:159390
Still, I needed an easy and safe fallback to demo the printer with the stock head. So I designed this. It quickly slides in place from the top and the bottom and it has no impact on the calibration nor on other printer parts.
Check my blog if you want to know better why I re-do some parts of the printer! http://www.tridimake.com/2013/09/design-compatible-parts-for-3D-printers.html
By the way, I added a very simple but quite efficient passive cooling heatsink to the head, as shown on the picture.
Just print two "castles" as they are fully symmetric. I used PLA, 0.8 mm walls and 20% infill. The thing is still very rigid because it comes as a whole instead of the existing plywood puzzle. No softening problems even at 245-250 degrees for a few hours (printing Nylon).
Update: without the fan, my PLA finally got a bit loose on the and was no more holding the bearings tight enough. So I uploaded a second revision with thicker walls, and I recommend printing it in ABS or Nylon and/or better isolate the aluminum plate/wood with a piece of Kapton to prevent heat from moving upwards in the caste ;)
The default should be OK but you may check that the main holes matches exactly the linear bearing dimensions (do not add lateral freeplay there, but you should not pinch them neither too much)
MOUNTING THE CASTLES
As you can see on one picture, I glued the two screws for the electronic board underneath the top plate. It is otherwise annoying to hold them.
Sled the two "ruined castles" around the existing rods (see the picture). Then insert the linear bearings from aside. Add two small screws with washers on both sides to lock the bearings. The design does not clamp them radially to protect them but they can be secured tightly laterally (better than with my ageing stock head walls - I certainly did not want to glue them).
Match the two parts and use the regular long screws through the ears to hold the whole thing in place like the stock head mount.
If ever the small screws that hold the linear bearing disengage with time, you will be able to flip them (insert them from the inside), add a nut on the outside, and tighten the bolt with a long hex key through the small additional hole on the opposite wall (revision 1 only!). The second STL revision has a thicker design but no more see-through hole. It also accomodates better two secondary inner bowden tubes.
You can also use the nut calumet here http://www.thingiverse.com/thing:44118 if you want your nut to be on the inside walls. I required no nut so far (~10 mount/umount).
Note that the top and bottom wooden plates are kept. The latter is probably wanted to protect the plastic from the heat of the hot end. Better add a large square piece of kapton to better isolate the thing.
This design also gets rid of the stock wall clamping bolt that pushed slightly and quite uselessly on the enclosed piece of bowden tube.
THE EXTRA DUMB HOTSINK
For the heatsink, I just removed the equivalent thickness to the PEEK element of the stock hot end (I did not want to create a reciprocal void at the end of bowden tube in the hot end that could help clogging it!). The setup is very efficient to cool down further the hot end, without impacting anything else -- still, be cautious as the aluminum gets quite hot!
Even on hour-long prints at 245 degrees C the PLA did not get soft at all. I could even touch the stock aluminum plate above the peek -- though be careful not to do so with the heatsink!
Finally, you may want to check an alternate design here that I just stumbled upon: http://www.thingiverse.com/thing:67517