Every now and then there is some popular personality that everyone seems to love - or hate- in the extreme, well beyond whatever the merits of that person. In the popular mind, that person can do no worng (or right). I believe the same dynamic applies to the old 'FPE/Zinsco debate.'
Let's keep things in perspective, and avoid the hysterical fear-mongering practiced by some parties - folks who just might have their own ax to grind. Here are a few facts to remember:
1) The "New York Consumer Safety Commission" study that keeps circulating only found fault with some two-pole FPE breakers; the single pole breakers operated properly;
2) Despite allegations of FPE falsifying their own test data, FPE products continued to pass independent testing by UL as long as they were manufactured;
3) As recently as 2005, an article appeared in IAEI news that dfated a lot of the anti-FPE assertions;
4) Somehow the same breaker design as that of FPE continues to be manufacturered, sold, and installed in Canada - marketed by the parent firm of Square D, no less;
5) Contrary to popular myth, FPE never 'lost' it's UL listing. As far as UL is concerned, FPE just went out of business; and,
6) Even if you assume problems with FPE, there is no basis to assume similar problems with similar products - unless you wish to assrt a flaw in the basic design. Such claims have not been made of FPE or Zinsco.
Not tripping? In direct contradiction of the statements made by Square D that their breakers are 'designed to trip at 80% of the handle value," I have measured numerous of their premium QO breakers operating for several hours at 100-112% of the handle values. This is not to be critical of the product; look to the trip curves and you will see that it is the statements of the sales force that are faulty. The sad fact is that we have NO way, in the field, to 'test' a breaker. This little detail is the one thing that bedevils the 'reconditioned' market, where they 'certify' to a standard that was never intended to be applied in that manner, a standard that has been discontinued because of such mis-use.
This is not to say that I like the two -very different- makes. My point is that there is a world of difference between what I like and what is allowed.
Of greater relevance is that, since both firms are out of business, such equipment is dated. Wine may get better with age, but few other things do. Obtaining replacement parts is an issue ... and you can forget about newer versions such as GFCI and AFCI breakers.
IMO, the presence of an FPE panel suggests that there are likely problems present far more serious than the brand of panel used - and most of these other hazards will not be addressed by a service change. You know the sort: overloaded circuits, double-taps, flying splices, grounding issues, three prong receptacles on ungrounded circuits. I say: focus on those issues, so the breaker will not HAVE to trip. (Sort of like a sailor making sure that he never needs to see if the life jacket works).