Okay, how is this for a response?
I have a Dell Powervault 725N I would trade you straight accross for that 4500. Now pay attention. How does this help you? Well, they are basicaly the same unit, so you lose nothing AND it is designed to run Windows, Linux, etc, like you want to do (drivers available etc).
Now
here is the bonus. I don't have just a plain jane 725N, I have a 725N with the CERC Hardware RAID card, midplane for same, and sleds for same. This was an expensive option in the day when these came out.
What do you gain? Simple. You get a unit that is pretty much the same thing, only better because it was designed for what you are doing and has a HW RAID card (better by far than Software RAID). What do I gain? Just as simple. I get a Guardian OS unit (which I like).
And yes, they are pretty much the same unit, just a few minor differences, making it not a Snap Server or directly compatible.
This is a win win offer. What ya think?