Tents can be designed so that zips are not curved, but rather operate in a straight line. Suggest this reduces the chances of snags or failure. Even for an inner bug net door on a side-entry tent, an upside down T shape is not as fancy as the curved shapes that TT and others use; but the T reduces chances of jamming, especially for the very light YKK no. 3 zips used for the inside net door(s) and you can pick which side of the T you want to open, or even open one side and all or part of the other. So there is a lot of flexibility. And the weight penalty of the T on a solo tent with access on only one side is negligible.
Have decided to use the rear vestibule on a side entry solo tent to extend the floor and add space, sans zips, which makes for substantial weight savings. While the front door has just one near vertical center zip, and the beaks can be opened together or separately on either side, for both convenience and further weight savings.
Fully agree with your concerns about the water resistant zips. They are not fully waterproof, and for small tents in bad weather are a PITA, Getting in or out of a tent in bad weather can be a challenge, and the ability to open or close doors with one hand is for me a big plus.
But for outer doors, usually on vestibules, you need a flap, or flaps really, because rain is better blocked if there is a stiffer narrow flap on the inside, and an opposing wider flexible one on the outside. Similar to what Montbell does on its bags in lieu of a large puffy inside flap, but have found the concept works well for outer tent zips, especially close to vertical ones where rain can come in under the larger outer flap.
Fully agree with comments about #2 zips. While the goal is light weight, more durability trumps weight on a shelter in severe weather. As for #3 zips, glad that both Warmlite and Quest were mentioned. While both are YKK, for some reason the Warmlite is more durable, but weighs very little more: 1.12 ounces per running foot vs 1 oz, not counting the pulls, which may vary in number.
Haven’t used the tooth zips on tents, but you can weigh the Vislons and see how they compare to the YKK’s. Agree that in blowing sand, the Vislons may be worth some added weight.
Hope this is helpful. For longer hikes, bringing along a small spray can of zipper lubricant or using it before setting out while cleaning the zips on an older tent may be a good idea.