IMHO the only two worth looking at are the Pure Freedom and the X-Line.
What you say is absolutely right. I've found that a 15 meter hose on your trolley is plenty for most houses. Place the trolley near the middle and leave it there while you move quickly from window to window.
This one from T L KILLIS looks good but for three things:
1 - it doesn't have a flow control. Instead, it uses a low duty pump. (But on the other hand that might be good - as it's one less thing to go wrong.)
2 - the handle telescopes - and the paint is going to get worn off the sliding joints VERY quickly.
3 - As it doesn't have the flow control and uses a lower duty pump, it should be £100 cheaper.