I have 2 reels and 1 of them is slightly hotter than the other,I’ve had a 5kw and it was more than sufficient especially if you return to tank between jobs but the 9kw with a single user should and does give me very hot water. If 40 degrees is not being able to hold hand under it then I’m getting 40 degrees lol,obviously it drops with the more hose out but with 20-30 meters out I’m getting 60 degrees measured with a TDS meter with temp feature.
I would always go for the 2 man though like I say hotter water with an option for 2 people working with it,the same goes for system in general far better to have it all setup for 2 people even if you are on your own if something goes wrong you have a spare reel-pump and the option to have help when you want from that van.