My concern for a team language choice is "How hard is going to be be hire people to write in this language effectively and how much will /they/ enjoy it?"
It's one thing to pick a language that I like and am productive in, it's another to choose a language for a larger team.
If you've found an full team of motivated and capable OCaml coders, great.
It has not been a challenging finding candidates for OCaml. For the most part, people who like OCaml are chomping at the bit to find a job writing it. And for those that don't know OCaml, a lot of really good devs are excited to try something different.