WE are getting this exact rainshower. We felt the 12 inch one in the showroom and the pressure is good. Our sales consultant explained that the early rainshowers acted like watering cans - the water just poured out without any kind of pressure. That's why it could take forever to wash shampoo out of one's hair. Newer rainshowers, including this Hansgrohe, have pressure - not like needles, but just a force that will help wash out shampoo. The Hansgrohe uses air to do this. So when I stuck my hand under this one, the water felt good - not sharp but it came out forcefully enough. We went with the 10 inch so that it's large enough to envelop the person while showering. Also, depending on how low you mount the showerhead, the cone of water gets larger. The price difference between the 12 inch and the 10 inch was large. If we need a large cone of water, then we can just mount the 10 inch a bit higher. Does that make sense? If you are in the Chicago area, Banner Plumbing Supply has a bunch of showerheads installed in a large, working shower. If you make an appointment for afterhours, you can come in your bathing suit and test them out! Along with the air tubs, whirlpools, etc... But we didn't do that ;)

I haven't mixed them myself, but I'm currently considering buying a Grohe faucet & Hansgrohe shower head/ diverter/ etc for our master bath renovation. I went to a store that sold both recently & compared the 2 finishes side by side; they looked extremely similar, so you may be able to pull this off!

If your fixed head is using all the hot water, is it simply a high-flow head? When flow restrictions first were implemented, high-flow heads were made compliant by simply inserting a flow-restricting disc into the head. A lot of users removed them. Would adding a disc help in your case? That issue aside...yes, components can be reused. Depending on their connections, soldered or threaded unions, it may be easy or difficult to break the plumbing joints. If soldered, consider taking the valve apart so heat doesn't damage the valve cartridge or internal components. You can sometimes get "ring kits", if that would be applicable to the valves you have, it'd be a good time to replace any o-rings in the valve to ensure fine performance for the next 20 years. If you can't replace, at least relubricate. Is it possible? Yes Would it look weird? That's up to you. It doesn't have to. Is it advisable? Yes. As long as you take care in the removal and reinstallation, all should be well.

I would suggest Grohe and Hansgrohe showerheads. We don't like fixed ones, so we'd have 2 sliding bars with hand-held heads: 2 people can take shower at the same time, plus both shower heads are adjustable. We have Hansgrohe Raindance, very nice head. For kids bathroom I'm getting Grohe Movario 36" bar and, most likely, Grohe Power and Soul Cosmopolitan/Contemporary shower head. Movario bar has wall brackets that also function as shower holders, so you can place shower head on the bottom bracket to function like a body spray without even moving a slide.