In my view a "moat" is something that protects the relationship with your customers. Insurance is a price competitive business and i doubt you can really have a moat here. If someone comes in and insures your belongings for nothing, you would switch in an instant. Of course right now nobody does it, but its just to illustrate that there is no moat.
Coca Cola has the taste and coffein in it as a moat. If you like the taste of coca cola, you will never switch if the taste of the other drink doesn't come very very close to it or you like the other drink more. And the coffein lets you crave it, its an addictive drug.
FFH right now are two businesses, the insurance and the asset manager. The asset manager also can't really have a moat and as they grow bigger they will not get better results than the market. Maybe sometime they will win big (like the duration decision), but sometimes they won't (like the shorting fiasco). I really doubt that they will not make mistakes again in some other form. Especially at their size its already really hard to add alpha forever.
So also no moat here.
BRK trades a higher multiples of book because they have operating businesses like the railroads, that itself have moats. (because rails in the US are limited for example, or the taste of see's candies).
But this is just my opinion.
(if there is a moat in insurance, it most come from lower costs, but why shouldn't this be reconstructable by someone else?)