Please do not comment on how using Windows itself is a huge downside. After several years using OSX, Linux and Windows, I can say that working on the latter OS is best for my needs.
I do own an iMac (27", mid-2010) however, and I am aware that I can install Windows 7 on it w/o using Bootcamp. Now, are there any caveats in doing so? E.g. I noticed that the iMac is heating up more than it used to under OSX. Maybe the arguably annoying abundance of hard-disk accesses under Win7 is a reason for that. Could this be a danger? Are there other issues known to SE users here?
summary: any caveats in using Win7 as main OS on an iMac?
EDIT: These helpful answers indicate that in general it might not be such a great idea to extensively use Win7 on a Mac because the hardware might wear off faster due to sub-par Win7 power management (compared to OSX).