3 shower heads in the private test at Electric Heater

We stayed at the apartment for a shower electric water heater with 21 kW. The water pressure is thus for technical reasons in hot water in the low range. So at low pressure, the water flow rate in liters per minute is also small - no real potential to save water by a "water-saving shower head." However, in such systems, the water heater Spray intensity is also likely to in the unkomfortabelen range towards low, especially in winter with very cold water supply to the heater. The areas "under armpits showers" or "Long Hair rinse shampoo" but require a certain strength of the water jet. Eco and comfort does not go there. So I was looking for a quality brand shower head, which because designed for saving water = designed for low flow, produces a still pleasant brewing Esch Wall and "upstream" to take a shower also suitable is therefore at low position shower head upwards under the armpits etc. to take a shower.
My test candidates and the results during warm / hot showers:

Grohe New Tempesta 28578001 Hand shower IV
Has 4 settings. Rain and RainO2 showed the same normal water gush shower result for me. Large exit surface, extremely low pressure of the water jet. Head-down posture of the shower head and shower up showed only about 3cm lax beam height, so you do not reach the shoulders really. The setting JetSpray works because exactly the opposite, very strong 4-5 jets do already hurt, because you have the shower head with long arms keep far away. The Massage spray setting is a mix between Rain and JetSpray but towards Rain with far too little jet printing for shoulders. Massage effect felt by the way = zero with me.
Conclusion: Not for my purposes.

Hansgrohe Crometta 85 Green hand shower 28561
Has only one Duscharteinstellung. Waterjet is sufficiently wide. Radiant intensity in noticeably uncomfortable weak area, showering under the shoulders are only ray height approx 8cm. Not really convincing. No acceptance found in the family.
Conclusion: Not for my purposes.

Hansgrohe 28562 hand shower Crometta 85 Variojet, 2 beam types, chrome
Shower Head setting NORMAL yields sufficiently wide water jet. Radiant intensity is much higher as the Chromette 85 green and the Rain setting in Grohe Tempesta IV. Showering under the armpits resulting beam height about 15 cm, is ok. The shower head massage setting gives strong shower spray, narrower than normal, radiant intensity sufficient waist with upturned shower head upward to the ceiling! Here the setting is not unpleasant despite strength, also has a lot more spotlight than the JETeinstellung the Tempesta IV. However, I have not noticed massage effect. With the two different spray patterns of demand / usage behavior will be fully covered in our family. Including cleaning the shower walls / bath by the strong beam in "massage" setting.

Conclusion: The Hansgrohe Crometta 85 Variojet with 2 spray patterns is in our 21 kW electric water heater system of the previously optimal showerhead.
May my review for you have been helpful.