Spring loaded extruder for Leapfrog Creatr

The Creatr from Leapfrog (www.lpfrg.com) has a fixed idler ball bearing. I wanted to replace this by a spring loaded type to allow better control over the filament feed and allow for an easier filament change.
After a few different ideas, the Mk7 minimalistic replacement extruder seemed a nice design to start with and here is the result.
Now changing colors is actually a fun thing to do ;)
Update: I found that the pressure on the filament was not always enough so I moved the spring and compressed it a bit more resulting in more pressure on the spring. I've tested this for > 100 hours with ABS, Taulman Nylon and PLA and had no problems at all.
Also added a longer filament guide towards the hobbed wheel, making a filament change a bit easier.
note: photos with the light green parts are v2, red parts are v1
You could consider building http://www.thingiverse.com/thing:321258 instead, this adds the possibility to print flexible filaments like Arnitel and Ninjaflex