If you never use a ladder how do you deal with plastic gutter creep ? Birds detritus on flat roofs ? Box gutters ? I have a set of customers that live in a row of houses that have a shallow pitch roofs surrounded by a parapet wall - when the outlets block it floods the houses so I have to get on the roof, walk round and clear all the birds nests and detritus. I do this twice a year.
Whilst I agree with the vacuum concept I think to offer a full service you still need to leave the ground having done the RAMS. If ladders are not for you then fine.
Out of interest what vac set up do you have ?