I've used canned twice now. The first time I just went right from the can into the mash. Clogged the crap out of my mash tun. What a mess and the beer sucked.
Second time I poured the canned pumpkin onto a baking tray and baked it first then put it into the mash. Beer turned out awesome and didn't clog either.
Not sure if the clogging thing is related to the baking or not, I kind of doubt it, but i thought the beer was better because of it.