My V2+ has about 50 hours, Last week I noticed cracking on the underside of one of the arms, around one of the four motor mounting screws (below). Upon close inspection, and under good lighting, I can see many of the motor mounting screws on all arms have "hairline" cracks developing. A quick Google told me this is not uncommon. I periodically check all screws for tightness, so it is possible I have slightly over-tightened them. However, I am fairly careful not to. I am continuing to fly, and I will keep monitoring the cracking. I will replace the shell once the cracking starts to really worsen. Replacement shells are around $100, and there is a good shell replacement tutorial on YouTube. The job seems to take 2-5 hours. Anyway just a heads-up to watch for this as your hours get up.