UPDATE 1 (19/07/2016): After posting this to twitter last night I got some instant help from the Senior Program Manager for SSRS at Microsoft. Thanks to Riccardo Muti for the info. I will update here again when Ive been able to confirm. Ill leave the post intact as Im sure others will go through the same thought process!
— Riccardo Muti (@RiccardoMuti) July 18, 2016
Having came through very little in the way of teething problems doing an in-place upgrade from SQL & SSRS 2014 Ive now come up against a doozy!
With the new configuration of SSRS there is no Report Manager subfolder. Instead we see this new RSWebApp folder.