I have played with a BK Medium for over 6 months now while testing the tip before releasing it to the public. It has not mushroomed or moved at all. I have shaped it only once. I scuff it before every league match and that's it.
If you have a good stroke and have no problem drawing your ball with the Moori M then I would say use the BK M. You may find with any tip that the softer you go you can get a little more spin or grip on soft or close shots but if you have to hit a power shot with 6 feet between the cueball and object ball... soft tips absorb some of the impact and you lose some of the spin. IMHO
Maybe, but the best draw I've gotten recently on a table length shot was with a house cue that had an Elkmaster on it.