Many IT professionals (not enthusiasts) including myself test and trial different Lin* dristros now and then, as they do with other operating systems - Solaris, BeOS, MacOS ... Some IT professionals have done this for decades and there's nothing fanatical about it.
Many IT pros have their own secret wishes and preferences of OS behaviour, architecture and performance, but they have to deal with what's the de-facto standard in their industry.
Speaking of Linux, first thing that crosses my mind is diversity of distros. It's good to have it as it brings innovation. However, it's good to have market leaders to be challenged with innovation. So I respect very much Ubuntu's success on the personal:desktop space, not a bit less then how much I respect Novell/SuSE's success on the enterprise:server space.
The good thing about Linux and OSS is that you could have the community-supported version of everything (so to speak) to use freely (according to licence).
I am very happy because all this enabled me to use:
- a full-blown enterprise-class server OS (CentOS) and a SOHO server OS (ClarkConnect Community Edition).
- a great technological platform for development of standard Web applications
- specialised distributions for particular use (for routers, firewalls, file servers, Internet kiosks, thin clients, mobile devices etc.)
and all that on different hardware platforms (x86, SPARC, ARM...)