Along my path as an IT god J I have found myself going back and forth on the appliance model:
Why would I want to buy an appliance, when it's the same software, and I can't choose the exact form factor or implementation of hardware?
I can just buy this box and plug it in and I have a solution. When I have a problem I just swap out the box and load a config file onto it.
If I use my own hardware I can use the same box for 5 things at once, thus allowing the box to do more with the same power and space consumption. Especially when I introduce virtualization.
I'm so sick of vendors blaming hardware, and having the battles between hardware and software vendors. The worst is when you have IBM, Microsoft, and vendor x all fighting. I also like the fact that I know my appliance will be in warranty, because it's a single renewal.
Not to mention some of these appliance makers that have been around for a while are starting to refresh hardware. That's a brilliant idea! I get new boxes with new features for a fraction of the cost of the older box!
Appliance is my vote now!