Re: Should we use WP/BP or another platform?
Take a look at https://wordpress.org/showcase/ for examples of some of the best sites built on WordPress. WordPress itself is a stable and exciting for building sites and CMSs on, and the showcase which I’ve linked you to will let you browse the highlighted best.
The ‘biggest’ BuddyPress installation – other than this site – that I am aware of, is GigaOM Pro.
I’m not going to sell the idea of using BuddyPress to you 
but perhaps if you make a short list of the key features and ideas that are essential, and things you would like to have, we can all comment the feasibility.
