Oven-ready lasagna noodles do indeed rely on moisture from the sauce to cook and soften the noodles. That being said, the same can be true of ordinary lasagna nooles as well. If you make the sauce rather soupy, and cook for the right amount of time, the noodles will soften. However, getting the right amount of moisture will determine the quality of the dish. I have used both the oven-ready, and regular noodles without boiling either, and have had spectacular results. But if you use too little water, there won't be enough to be absorbed into the noodle, or if there is, the fillings may be dry.
Use too much and you sill have runny fillings.
As for using fresh pasta (uncooked, just maid, and moist) they will cook faster, have more body, and be a little thicker that store purchased product. A thicker sauce can be used with the fillings and still result in a great end result. And the dough is soooo easy to make. The downside, the noodles are fairly delicate and require a bit more care in the handling.
Hope this helps.
Seeeeeya; Goodweed of the North