For the last 2 years there's been the request of a large rain-shower and handheld on slide bar or body sprays in ever new home I've plumbed. In the quest to find a brand that I felt was easy to install / repair / get repair parts for / get matching accessories for, I've used Symmons, Delta, Moen, Grohe, Kohler. In conclusion I always use the Moen faucet for this type of shower set up now. I don't recommend against the other brands, just that the moen best fits the needs of me and my customers.
I use the Moentrol pressure ballanced with a 3-way built in diverter. It is available as seen in the pic with a standard shower head and body sprays, but you can also just purchase the control valve seperate and the matching handheld and rain-shower.
The valve is only 1/2" feed, but I've never had any complaints about the pressure. The bottom handle is pulled out for volume control and turned for temp. control, while the top is turned for diverting. The diverter allows you to have one shower running and then as you turn the diverter it will gradually open the second shower head. So both showers can operate at once, continue turning to shut the first shower off and only the second head will be on. With the variable setting you can apply more pressure to either head or make them balanced.
Recommend your pressure be @ or above 40psi with properly sized water lines or you will have very noticable pressure drop with both heads on at the same time. I installed this faucet on a remodel using a water well with 20/40 pressure switch and I had to turn the pressure up to 40/60 for satisfactory results.
I use the Danze 10" shower head with the rubber tips for easy cleaning and the matching Moen handspray.