Electric reels seem a bit uneccesary to me.
I've never had a physical problem/tiredness from reeling the hose in.
At £650 a pop it's a lot to spend surely?
Also if it snags won't it burn the motor?
I too made one for about £50
But no I don't think it is too much of they last a few years.
You will save a small amount of time but mainly you will save effort which should mean you are fresher at the end of the day and maybe you will clean an extra house if you are not as tired. Bit like clx vs extreme, extreme won't me much quicker really but will be easier and less tiring.
Worth every penny imo