Mixed bag o'blessings..
Got the screen doors in our Cimarron, me, my wife, and the mud boggin dog. Not total bug protection, pitch it a few inches off the ground for airflow, but it does slow a good chunk of the horde. And when the horse flies are out, and every other carnivorous bug in force, slowing most if not all down is nice. Also run a Bear Paw half nest inside the tipi, which does keep all bugs at bay once it,s zipped up.
Down side is the extra 10 ounces. 10 ounces here, 5 ounces there, and you end up with a few extra lbs way quicker than you,d like.
Odds are you are going to be pitching it off the ground to keep condensation to a minimum, so the screens won't stop all the bugs.
If you know you won't be getting a nest, screens are probably a worthwhile addition weight and cost wise. If you are planning to get a nest, mostly just an extra 10 ounces to drag around.