It's hard to compete with RStudio for best IDE for R. I stick with vim-R-plugin for most stuff but RStudio is so helpful for making presentations. But competition is good.

Excel add-on, on the other hand, seems very interesting. I lost lots of time in Excel before I decided to get rid of it instead in favour of R+SQLite. I wonder if it would be possible to make the add-on work under wine though.

Edit: just tried to get FasteR add-on under wine. Unfortunately, it requires .NET 4.5 with which I didn't have much success previously...