Zpacks Backpack – Hydration Port or not?

Yes. Why not. Someday i may lay a platy with a tube at the top of the bag to drink. No to the sleeve.

If you don't use a hydration system/never plan to use one, then maybe you could go without. Not for weight savings or anything, but because it's one less hole to let water into your pack. Especially if you get one of the cuben hybrid packs. You basically have a dry bag once the port is eliminated. (If you seam seal the pack)

I didn't get one on my Arc Haul because I don't use a bladder. The side pockets are generously sized to fit 1l bottles, and even 1.5-2l depending upon bottle shape. I find the 32oz Gatorade bottles — which have a short, fat design — fairly easy to remove and replace while walking. I experimented with a bladder with my Flash 62 and found it to be a hassle to remove from the pack for refilling (had to unpack about 2/3 of the stuff in my pack!), it still requires another hard bottle for dipping in a stream or lake, and it weighs more than my usual set-up of 1 Gatorade bottle plus 2 1l Platys for collecting dinner and breakfast water. The tube also freezes when it's cold out. Too many negatives for me.

What Bob said.

I chose no port. I don't use a bladder, if I decide to then I can stick it in a side pocket, and a port theoretically could let rain in so decided against it.

yes. Many times these days I am carrying more water than I actually need (for the kids.) The younger girls seem to derive pleasure from sucking water out of my hydration bladder, or my wife's. The 15 year old boy is wierded out by the whole thing – for good reason, I suspect.