Here are a few things you might want to consider.
https://github.com/nosami/Omnisharp (for Autocomplete and Science, just don't try to use Unitiy's mono distribution to run the thing)
- let g:Omnisharpstopserver = 0
- Turn OFF "Open new window on reactivate" setting in MacVim. Otherwise you will always get a new window when you open a file. Very frustrating.