I did my first full second storey gutter and fascia clean last week. It came up perfectly well from the floor with a superlite brush head. You can work well round the brackets and get deep enough at the back.
Put it this way, the customer paid £98 for the gutters and a window clean and was overjoyed, which is what counts.
As regards comments ref ladders vs poles, what we have on this site is a set of very entrenched opinions. Neither side can see the other's viewpoint. You'll never hear a WPFer saying that someone up a ladder might well do a slightly better job in some cases or vice-versa. All you'll hear is that the other way is utterly useless and that you'd be barking mad to try it as it'll be the worst job ever and you're an offence to the human race for ever suggesting it could be done your way.
In my opinion, what matters in the long run is whether the customer is happy, whether you're up a ladder or standing on the floor.
Use the poles, it'll be fine.
Vin