Would the world end if I fitted a 200mm x 57mm shock to my Blur 4X (which is meant to take a 200mm x 50mm shock)? Would I just get a little bit more travel? Any risk of f*cking something up?

Dave

Risky. An extra 14%(ish) of travel could foul something somewhere in the suspension. Are you sure all the bits can move freely that much more?

What he said ^^^^^^^^^^^^

Take your shock and compress the suspension and check it out.

Interesting thought. Fit it and say if it clears everything, you will find it jacks the rear to an odd position, so you'll need more sag to get the headangle right.