I never tried the recipe, but have enjoyed fresh tomato based sauces for several years. We use whatever varieties that are ripe in the garden. My wife does leave the seeds in and no one can convince me they make the sauce bitter. I don't think the cooking method matters that much. Adding fresh to canned makes a good sauce. Using only fresh also makes an excellent sauce, better than mixing in canned in my opinion. Simmering in the pot to reduce volume by half, rather than halving and baking whole tomatoes also works. My wife uses no oregano in fresh sauce, only garlic, salt, pepper, oil and fresh basil. Put it on pasta or pizza. It is miles better than any canned tomato sauce.
The oregano you recommended is doing well, stopped spreading out and adding a little height finally. Thanks!