I have sucessfully made manicotti without preboiling the pasta. But I make mine with a sauce/meat/cheese filling, and cover with a tomato sauce before baking. If making without pre-boiling the noodles, then I make the sauce very wet. The extra moisture is absorbed into the pasta and softens it, just as if it were pre-boiled.
I wouldn't make a cheese-filled manicoti this way as the cheese would be overwhelmed by the extra moisture and I would think it would become too runny. But I've never tried the no-boil method for cheese manicotti or canolli so this is just a guess.
The only advantage to making manicotti without pre-boiling is that it's easier to stuff the tubes without breaking them. So if filling with anything other than the sauce/meat/cheese filling, I would pre-boil them.
Oh, and a tip; if you have a cookie press that has interchangeable tips, leave the tips off and use the press to "inject" the tubes with the filling. The is so much easier than trying to spoon the filling into the tubes.
Seeeeeya; Goodweed of the North
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