I guess I've not had the same experience with Pantaenius as some others but for us they have been easy to work with and very responsive to our requests to change cruising grounds.
I've been fortunate to not have a claim so I can't speak to that end but I have read (here, I think) that their post-lightning-strike service was very good.
I know all I have to do is write an email to them and within a day or two I get a new quote for our cruising grounds when we go from U.S. to Med. to Caribbean (which is now a very pricey market).
Without wanting to start a negative discourse, I would not be a person to warn you against them but rather to give a good in depth look at their merits and the scope of coverage they have.
So far, so good with them and the people I have dealt with have all be friendly and accommodating .. even when I "oopsee'd" and sailed out of my coverage area unknowingly :).
SM 209, Adagio