Wishenwell, we didn't see a need for a diverter. We've got the hot and cold supplies going to the thermostatic valve, then there are two outputs from there- one goes to a volume control for the rainshower, and one goes to a volume control for the Movario handheld. With that arrangement, we can independently run both showerheads, plus have independent volume control over each. The only thing we can't do is independently set different temperatures, which isn't much of a loss. The diverter systems get pretty complicated if you need to plumb anything other than "one or the other". The other benefit of having the two volume valves, was that it came out less expensive. :-) Hope that helps.

Sorry I'm late to the party, but I may be able to chime in for anyone who has similar questions regarding Grohe & Hansgrohe. I am in the process of a renovation and wanted to go practical high-end (Im not sure what that means either). To make a long story short, I obtained a series of faucets: Dornbracht Tara in chrome, Hansgrohe Focus 31730 (chrome), Grohe Atrio in Satin Nickel, Hansgrohe Metro in steel & and a KWC Systema in steel. I also purchased a Everpure drinking water faucet in nickel. My mother had purchased the Dornbracht for me (yes nice gift) and ultimately this is the faucet I chose to put in the bathroom. But I had purchased a Hansgrohe Focus that I was planning on having installed. As well as a Everpure faucet for my Everpure water filtering system (quality of the Everpure was on par with the Hansgrohe Focus you will read about). When I received it (Hansgrohe Focus chrome) and put it in my hand it just felt so light and insubstantial. I am not saying that it felt "cheap", hardly, it is a nicely made unit, however I was not impressed with it. However it was certainly nicer than anything I saw in my local Home Depot. I ultimately decided I will put it in one of my girlfriends rental units. Next, I purchased a Grohe Atrio which is similar in style to the Dornbracht Tara. Now let me remark on the differences between the Hansgrohe and the Grohe: First of all, the Grohe feels considerably heavier and more rigid. The routing is cleaner in the rear and the tolerances are tighter between the parts. The handles also feel much smoother to the point you actually can distinguish this. The plates are also heavier and more "substantial" than the Hansgrohe ones. The brass diverters are also heavier on the Grohe though the Hansgrohe ones are visually more appealing. For the kitchen I purchased the Hansgrohe Metro because I liked the way it looked and it had pretty good reviews. The faucet itself is definitely of higher quality than the Hansgrohe Focus I had originally purchased to put in my bathroom. Though I think the pull-out spray spout feels "plasticky". I decided I wan't happy with the quality for the price and plan on returning it. I ended up going with a Swiss made KWC Systema, the quality is sick, so is the price. Throughout this process I have looked at quite a few Grohe and Hansgrohe pieces. I think there is no question that Grohe is the superior product.

I have measured flows on my hand held shower head: max flow = 8.5 l/min, min flow = 5.6 l/min. (max flow=volume control all the way clockwise, min flow=volume control all the way counter-clockwise, flow reduction of 34%) Even with the hand held shower head removed (no restriction at all, free flow out of the hose) my min flow stayed about the same while max flow obviously have increased therefore bumping up flow reduction to something higher than 34%. Since my max flow is fine for me and I would like to see my min flow decreased, the solution of removing flow restrictor will not work for me. There is an option of adding flow restrictor to the Smart Control Cartridge which will reduce max flow, but it should hopefully also reduce min flow which I would like to see. I might try it, but it is a bit painful to disassemble the whole setup. Hoping this info helps someone.

"What is it about this myth that causes it to refuse to die?" The fact that it's not a myth. They do manufacture products exclusively for the big box stores that look just like the better versions. Sometimes they even have the same name. For example, Delta's kitchen faucet Foundations, #10900LF is listed on Delta's site as "only at Lowe's". They also have a Foundations faucet #B1310LF that does not have that designation. As millworkman said, if the item numbers are the same, then they are the same faucet. But just having the same name does not mean they are the same or manufactured to the same quality. I think you will be better served with a slide bar. Your grandson will not be 5 any longer next year, or any year after that.