Dirk Eddelbuettel has been contributing to Debian as a developer / maintainer for almost two decades. Most of his open source focus these days centers around R to which he has been contributing for well over a decade. He works in Chicago as a senior quantitative analyst, and holds a PhD in Mathematical Economics from EHESS.
What I found hardest about using Git the first time was… best described by this piece of satire as git really is overly complicated.