The X2 comes with either a R-8 or MT3 spindle taper, with my mill having the MT3. Aside from there being more tooling available for R-8 it's biggest advantage that it's self releasing. To release an MT3 which has been over tightened will require much beating with a hammer on the drawbar. Even release a lightly tightened MT3 means at least one hit with a hammer. Personally, I don't like hitting my mill with a hammer.
However, even though I could change the spindle to R-8 for $60, I like that MT3 offers me more Z axis clearance. I also don't particularly want to spend $60. To allow me to eject the tool without having to use a hammer, I bought an 8" C clamp for $14 and cut the end off to give it enough clearance when there's a tool in the spindle. To eject the tool I simply loosen the drawbar, put the clamp in place with the base on the bottom of the spindle and the top of it on the drawbar, and then tighten it until it pushes the tool out of the spindle.
UPDATE: I modified the bottom of the clamp to better support the bottom of the spindle.