In my summer job, I'm working on Windows based machines and connecting through ssh to a front end SUSE 10 Linux box. Through that front end, I'm submitting computational jobs to a *nix farm.
I'm also using java (Eclipse as an IDE) and a programming language called R (emacs) (which is pretty darn good for what it is) to create the code for computation.
All of this, I've never really done before this job. I have to say, it's pretty darn fun for a change.
Now, crossing over to this other side, I can understand the arguments a bit more (java vs .net, *nix vs Windows). Though, I still prefer Visual Studio (intellisense ftw) and C# (java packages are so odd).
While I do agree that you shouldn't ignore the competition, I do believe that at some point there needs to exist a cut-off. You shouldn't have to acknowledge every bit of competition in every decision. The same should go with the whole computing world in general:
there doesn't have to be dozens and dozens of the same technology or product implemented in similar, often exactly the same, ways.