For anyone keen on DIY who is interested in comparing the 2 makes, I have found a very real difference in performance. I am taking about the digital boxes, not the bars that go in the shower or an electric heater on the wall.
I have an Aqualisa in one shower and needed to replace a Grohe unit in the other shower where the thermostatic cartridge has failed.
Replacing the cartridge wasn't difficult once you paid £44 for the box spanner that Grohe sell and which you do need but then you have to re-calibrate the unit and that is impossible. Trying to get in touch with the local agent - based out of Worcester - was also impossible Tech support know little of value (other than how to identify the need for the £44 box spanner) so I cut my losses and looked for a replacement.
I always thought Mira and Aqualisa were very similar. It turns out they are not. I use mains pressure (not combi but real mains + a tank) and have a longish pipe run for the showers which goes over the ridge in the attic. The first unit on the run is the Aqualisa. It works perfectly. No variation in pressure or temperature no matter who uses water elsewhere in the house.
6 ft straight on is the Mira Vision. Stand under that while someone opens a tap and you get scalded or frozen. Mira sent an engineer who said its the pipework. He rang tech support who, without pics, said its the pipework. I asked why neither Grohe or Aqualisa had the same problems and got some gooklydegob noises. The simple fact is their box isn't up to the job
The other very strange fact about the Mira is the max temperature the shower runs at out of the box. 49C. Every other manufacturer knows that 39C is the comfortable safe max. 49C is painful. You can set it lower but safe should be safe as installed with default settings IMHO.
Anyway. If you are debating between Aqualisa and Mira and Grohe digital showers, I hope this little bit of factual, real life experience helps you decide. .