I have a Gröhe thermostatic valve which came with the house. It's somehow broken such that you can't get the water as hot as advertised unless the dishwasher is running (?). And it's installed behind tile, so we can't just get a plumber to come in and replace it; we have to also line up someone to re-tile the shower immediately afterward.

We also have a pair of Gröhe sinks. We had to replace all four expensive, proprietary faucet hoses one-by-one as they ruptured. And then a couple more. It turns out they're short enough that it's hard to install them without kinking, and that eventually causes them to rupture.

I'm not a Gröhe fan.

(It also takes several minutes for the water to come to temperature in that particular shower, though it's only about 10 feet away from the water heater. I think the sink fixtures are affected too which suggests it's not all the shower valve's fault. It might be that we have pipes that are indirect and/or way too high-capacity, such that the total volume of water to drain between the water heater and the bathroom is excessive, and this is particularly obvious when using a low-flow shower-head.)