I did mention that extension; and the bug I found right away :(

Roslyn isn't just about being open source; there's functionality like the Diagnostics/CodeFixes that make it trivial to do some really useful things, which are significantly harder using the F# source.

Overall my conclusion is not that F# is bad; I really love it; but there are some niggles for me still... Mostly around the level of investment from MS :/