As the inventor of the deviator and having used them extensively for the past 15+ years in many centers around the world including Vela on Aruba and my own shop, Bonaire Windsurf Place on Bonaire, I can assure you that it is a almost a mythe that your mastbase box gets ripped out while using a Deviator. Afterall we only have seen this occur in just a few boards over the span of all these years and this was because the box was inserted while the fibrecloth around the box was insufficiently impregnated by the epoxy resin.
If I may suggest the best combination we have found in all these years being in the rental business full time (and not just seasonal) is to buy a fibreglass nose cone and to use a deviator. I gaurantee you that this combo is bomb proof !
If you want more info and tips you can visit my website at www.thedeviator.com
There is no other product out on the market which protects the structure of your board like the deviator, end of story !