Nice boats, generally speaking highly regarded.
In his book Bob Perry reckons the ketch was a better choice than the sloop.
Yoou should get his book if you are thinking of buying a P40/41 but also a google search should bring up plenty of links to this design.
LaBatt , one of the old timers here has one and is worth talking to.
There is also a Passport 40 Owners site out there somewhere.
In the older models you need to watch out for teak deck problems and iron tanks. While it's not a Perry design we recently went through the procedure of looking to buy an old (1980) P42 and ran away from her because of those very problems. Cost of rectification was horrendous. I'd also prefer one that had a Yanmar engine.
Otherwise , and presuming that by now some of the slightly dodgey Taiwanese hardware has been replaced, they have absolutely beautiful interiors, a nice hull shape and no major vices as far I know anyway.
Those are my principles, and if you don't like them... well, I have others. Julius Henry Marx.