Hybrid !

I've dealt with warranty claims for carbon masts sure ... it does happen occasionally.   It even happens to that relatively 'SuperStiff' alloy M7 with some who also 'forget' .... IF you maintain lowers at a regular setting and then rake the mast via forestay you, of course, have to take up the slack as you switch to offwind.  If you don't the lowers hold the bottom of the mast firm but the upper sections are not fully supported offwind by the (still) slack shrouds - the rig pivots at the mast/lowers attachment and goes 'over the front', it inverts and then can easily break.  You can get away with it in lighter conditions but add a gusty 20+kn and maybe a few waves and the odds shorten quickly.

You could specify a very strong (usually stiff) carbon stick of course but can also lose much of the benefit from having a carbon one in the first place.  Some makers eventually end up having to do this to still benefit from the 'carbon' marketing label while maintaining a commercially acceptable level of 'durability'.   If you have lowers you have other options  that avoid an over-stiff stick and all that entails.   If you do not have lowers – well the mast is inevitably heavier and stiffer and possibly larger in section all other things being equal  Hence the attraction of alternative de-powering approaches that can minimise risks yet maintain high(er) performance.  One way is to have an (already) raked rig coupled to a sail design that really responds to Cunningham to blade off the roach -  important to get the battening right naturally.  Another very useful one is to look to slacken off the lowers 'on the fly' to allow more regular bend in the lower mast upwind rather than depower via forestay raking  - you get a very similar effect to raking via forestay adjustment but it can be more forgiving in terms of necessary (and timely!) crew input.  In fact I think much of the benefit of raking via forestay actually comes from the fact that this naturally slackens (set) lowers (allowing more mast bend etc) - So why not leave the shrouds and forestay alone and just adjust the lowers ? You do need a stick that is suitable of course ....  As an extra safety feature you can also set up an extra line that runs from the bow forestay fitting to the lowers attachment on the front of the mast.  This can be used to inhibit, or at least provide a maximum limit, on any tendency towards mast inversion.

Anyway the point made here is that there are usually more than one way ....