It'd still be an issue... He's saying the pressure to the guns would be equal. If you have a 25 psi back pressure and open up 1 nozzle, you've got 25/(area of 1 nozzle) of pressure coming out. That's gonna blast! If you've got 10 open, you've got 25/(10* nozzle area) of pressure. It might be kinda dribbly.
Is there any solution other than having an individual pump for each gun?
You don't evne need the main body, just the add on parts! http://www.amazon.com/Orbit-58874N-Extra-Complete-Watering/dp/B003LY4I2I/ref=pd_bxgy_lg_img_y
This project Ray's Hobby Projects: Minty Water Valve Controller seems to use the same valve, and from what I read it seems to be a 24VDC latching solenoid. I was told by previous posters that a latching solenoid would just over complicate things.
Sean