In regards to valves the only issue with the ones that come with is the handle length. Sure being plastic they might not last as long as a brass one but they’d last years based on what they are used for. The advantage of brass would be a longer handle which would provide more control, via a longer lever. But once you find the sweet spot, it’s a breeze. Again, this is ideal as a one person stuffer.
As mentioned I use air and use my RV pressure regulator, which I think is 38-40lbs. For the most part I stuff same day, but have also done next day. I have noticed that more PSI/valves adjustment is required on next day or any sticky mix. Super thick I’d have to ditch the pressure regulator. Using water you need a drain line, with air I just use the valve. I don’t mind the sound of 40psi hissing out, but if you have a crowd, or someone easily annoyed, you can attach a hose and exhaust elsewhere.
One advantage with water vs air is resetting the plunger if I remember correctly. I just use a long wooden spoon and manually push it down the tube.
A few other tidbits...
-I use crisco on my o-rings and lube up the plunger before inserting. Make sure you clean well as that stuff doesn’t wash off easily and can build up.
-I marked a stop point with a marker on the tube so I know when it’s at the end/bottoming out. I think it’s designed that within the pressure limits it just bottoms out and stops stuffing anyway.
-Like any stuffer, you are left with a burger size patty at the end/in the tube. Perfect for the fry test, but not always desired. I use a 4” filler ring, cut from a 1/2” white poly cutting board to fill the gap. Not my idea... saw it somewhere on the google net.
Good luck and enjoy. This thing made my sausage stuffing life a lot easier. Cheers!