The 'no mixing sprinkler styes rule' doesn't have much to do with pressure, its about application rate and not having one section soggy while the other section is still too dry. Most drip sysems can handle 50 psi, if you're going to mix the zone anyway, I wouldnt bother with a pressure reducer unless your using some real cheap drip brand, it won't affect the amount of water coming out of the emmitters.

It's easier to mix a zone with rotors than say spray heads. You can usually nozzle your rotors down so that less water comes out, nozzleing them up might not work, depends on how much of your availabe water is being used already. Drip emmitters also come in sizes. Usually .5, 1 and 2 gpm. really some testing is needed. How long do you usually run the lawn zone and how often? You'll need to choose an emitter size to water your shrubs in the same amount of time. There are also other styles of garden emitters that are individually adjustable, often you can shut them right off, but i find most of them put out a lot of water... if I have to mix a spray zone, thats what I typically use. Hope the rambling helped, I can clarify if it didn't!

Ack! I meant gph on the emmitters. Thats gallons per hour. Rotor nozzles are measured in gpm, gallons per min

That does help, thanks. I had gathered that the mixing could result in floods and deserts, which is why you wanted to avoid it.

I think I'll end up playing with the GPH on the emitters to make sure I get enough water to my plants. These are all new heads, so I'm not sure what my run times will be yet. I'm setting out cups to get an inch-per-hour rate if I get a nice day.

If it doesn't work, I have an open valve and can dedicate a zone to drip, but I'm trying to avoid digging. Long story, but I'd have to trench it all by hand and that's a pain! Thanks for the insight.

Well, I tied in a few drip emitters as described above, on the other side of a 25 psi pressure regulator. And it waters my plants with the zone, and life was good. Then one day I noticed that zone was "stuck" and still spraying.

That valve sticks open, and I don't know why. Not all the time, but most of the time. I took it apart, and removed a few (4-5) grains of sand. Everything looked good on the inside. The problem still exists. The valve (rainbird) is less than a year old. I've read air bubbles can cause this to happen, something with a diaphragm getting stuck. If I tap or shake the valve mainfold, that zone closes, which may suggest air bubble. My theory is that since the drip emitters siphon out water after the valve shuts off, that must have something to do with it. However, if I had a dedicated drip valve, the siphon would still exist. I'm not sure where to go from here.

What I've tried:
1-cleaning/checking valve
2- turning down the "water in" screw to the bear minimum flow
3- changing order zone valves open

Any ideas?