Any CTO signing off on $37,500USD a year for 150 developers, when you can get unlimited developers on Bitbucket for $2,400, probably needs to be fired.
The price of the Github's service is ~$20.8 per developer per month. This is about 10-30 minutes of developers time worth per month. Adapting to Bitbucket's workflow and learning its UI would take much more time.
If you've hired a developer for whom using Bitbucket instead of Github takes 10-30 minutes more effort a month, you need to rereview your hiring process.
