Equity_Research_Exit_Opportunities

I am moving into Equity Research after a couple of years in the energy industry. I love the intellectual stimuli the work provokes, but with the energy industry on the brink of a slow but sure overhaul, I err on the side of caution. The financial modeling skills, in depth critical analysis of a company and forming ones own view seems like great skills to acquire and in my view can be well applied to commercial/business dev/strategy roles. I have even seen people moving to in house M&A of different companies as well. My question is, with regards to exit opportunities. Given the macro view of the energy industry, does it seem prudent to do Oil Field Services (OFS) research and develop that expertise? Would covering Big Oil be any different? Also, do companies(banks) put restrictions on joining the companies one covers? Any other views on exit opportunities apart from buy side, Asset Mgt, Hedge Funds would be greatly appreciated.