What ever you are using for regular valves should be fine for the master. The idea behind a master valve isn't that you try to get a "more reliable valve". The idea is that two valves have to fail before your system wastes water.

I really like the California Faucets thermostatic valve i used recently - well built, separate controls for two outlets, both with higher than typical flow rate, and a large central temperature control lever or knob surrounded by embossed numbers for ðF styled as if it were a fine watch. They also have a huge selection of styles, finishes, and either round or rectangular bezels. I've also used one of the Hansgrohe thermostatic valves that used their universal box - also quite nice, though I think a chrome-plated plastic bezel is a bit cheap for something priced as an upscale item, and I'd like temperature markings (isn't that part of the point of having a thermostatic valve, knowing what temperture the water will be?) This one uses a single lever to control 2 outlets, but it still works well and incorporates water volume and a diverter into the same control, and yes it can send water to both outlets at the same time at any proportion. It's designed so the innards of the valve are all accessible from the front, and can easily be serviced or replaced without ripping out tiles or the back of the wall. The Kohler and Grohe thermo valves I used a few years back have both been discontinued, so not much point discussing them here (there were both good).

Both companies are recommending softeners that are way undersized. They will waste salt and water and regenerate more often than is optimal. With your water conditions and the number of people you'll need to remove about 7680 gpg hardness per day. That's about 53,000 gpg every 7 days. The 1.5 cu ft softeners, recommended by your two companies, can't achieve that K. Best their softeners can do is 45,000 and that's using the maximum salt dose of 15 lbs/cu ft of resin for a total salt dose of 23 pounds each regeneration and you'd be regenerating twice a week. That is a salt INEFFICIENCY at Grains of Capacity PER lb of salt = 1957 A correctly sized and properly set up softener regenerating once a week would use 14 pounds of salt regenerating once a week for a salt efficiency at Grains of Capacity PER lb of salt = 3800 As far as control valves, the Fleck 5600 has proven to be one of the most reliable valves in the field and AFAIK there are no problems with the turbine. Both the 5600 and 2510 are 3/4" valves so it's be nice to know what size plumbing serves your house. The 5600 is limited to use on 12" tanks and under so if you get a correctly sized softener you can't use a 5600. A 2510SXT would be an excellent choice and so would a 7000SXT. As far as corrosion, The Clack and the Fleck 5600, 2510, and 7000 are all made of exactly the same material... Noryl and have similar designs as far as motors and circuitry so if one is prone to corrosion then they will all be susceptible to corrosion... but I've yet to see one of any of them corroded unless there was a water leak that sprayed them. Clack has withdrawn their control valves from internet sale so the only place to get them is from an assembler like Hellenbrand and then you are forced to get parts from them as Clack OEMs specific designs for them or a legitimate local B&M water treatment dealer. The Clack is a good valve but there always seems to be someone everywhere that services Fleck and sells parts and you can buy Fleck parts all over the internet.

Once the softener is installed, add 2.5 gallons cold water to the brine tank. Add a couple of bags of salt. Enter the master programming mode on the valve controller and set as follows: 1. DF - GAL 2. VT - St1b 3. CT - Fd 4. NT - 1 5. TS - U1 6. C - 26 7. H - 19 8. RS - SF 9. SF - 20 RC - 0 DO - 8 RT - 2:00 (or other time when you are unlikely to use water for a couple of hours) BD - 60 BW - 10 RR - 10 BF - Find your BLFC sticker (look at the attached pic - the sticker is inside the red circle) If it is 0.25 GPM then set BF at 10. If 0.5 GPM set at 5, if 1.0 gpm, set at 3. Ensure all days are ON, unless you have a specific day of the week when you need the softener to NOT regen. CD doesn't matter unless you set a day to OFF in step 14 FM - t0.7 should not be available Once the valve is programmed, step out of master programming mode and set the clock to the correct time. Manually place the softener in regen. Allow the backwash to finish, then manually step through the other steps. Leave each one on just long enough to verify it is working. Allow the fast rinse to run for about 5 minutes - you will have added just a bit of brine during the brief time it was in the brine draw step and you will want to flush that out. Step into service mode and enjoy your soft water.