How high do you need to go?
I've done a bit of cladding cleaning, and in my experience if it can be done with a powerwasher it will take less than half the hours to complete the job. The only problem is that the extension lances aren't really practical much above 20' high, so we normally WFP the higher stuff (With plain tap water,.. perhaps a bit of GG3 direct on the brush if it's really bad) and powerwash anything we can reach with the long lance.
If its a big job, the time saved would probably cover the cost of hiring the gear?