The user sharing features are defined by the OS as opposed to the hardware, so you would have the Mavericks standard two VNC connected users and as many unix/ssh connected users as you care to log in.
Performance wise, it's not clear until something ships but the specifications, storage speed and memory bandwidth can only make sharing more easy than compared to existing hardware even if the OS isn't heavily optimized at the initial release.
As to your implied question of the best use of capital, I'd get each developer their own Mac - beg, borrow, steal from whatever budget you have to get a used Mac for each to call their own and then get a continuous integration build server for the group to offload compilations. One Mac Pro running OS X server would be ideal there but a Mac Mini Server would also help you offload compiles when a local Mac is slower than desired.
At that point, you can make a business case on the salary you pay each developer to sit and wait for X builds per week and decide to allocate hardware based on demonstrated need rather than a hunch.