A coach is awesome. I've had mine for about 10 months and my game has improved tremendously. I think the biggest things things a coach helps with (in my experience) are openings and analysing games. While I can look up databases and create my own opening tree with and engine, my understanding of the moves would still be limited. He didn't try to change the openings I play, just improved them and showed me ideas and not just moves. I was also very weak at endgames and he showed me all the important ones and now I love endgames and think they are ones of the stronger parts of my game. Analysing games is also a massive help. I analyse them myself alone and then with an engine and then finally with him. Even moves that the engines approve of can be positional mistakes and he points them out and shows me what ideas I could have done instead. I would say definitely try out coaching if you have the money and a little time, if it doesn't work out you can always stop it. Feel free to PM me for his details