Have just checked out their policies; they have very woolly exclusion wording "dogs with vicious tendencies" - if you ask behaviourists, they probably would say that all dogs have the potential to be vicious/aggressive, it just depends on whether they have been subject to the necessary trigger
Also, Petguard only pay for 4 weeks of prescription diet - this is one of the biggest things that varies between different policies, and I'm not sure how 4 weeks compares with all the others, but I know some policies still offer lifetime cover for prescription food