Both are equally easy to maintain, depending on what OS you have studied, etc.
Technicians trained in Windows only, will find Linux a little harder to maintain, just as it a Linux only guru would have a some trouble maintaining Windows.
Additionally, the demand for .NET frameworked application capabilities is not an "unfortunate" thing to say the least. .NET is not only a widely accepted framework for application development and deployment, but is very easy to develop, and understand.
You can actually grasp and begin programming in almost any .NET language, alot quicker than Perl or PHP.
The only downside of .NET is that it's not yet cross OS compatible...but there are tools and additions that are beginning to enable this. That part of it is moving forward a little slower than most .NET developers would like, but it's still moving forward.