[mxz3000]

we have a massive mixed c# and f# codebase at work.

F# is not magical. Yes it's an ML, but frankly, C# is better in every way, to the point we're slowly moving away from F# entirely.

The main reason is perf, it's really easy to shoot yourself in the foot with performance in c# (e.g. huge allocations, accidentally evaluating seqs twice, etc). Also IDE support for F# sucks when you get to the hundreds of project solutions like we have.

For side projects, sure use F#. For everything else, stick with C#.