It sounds to me like right now the thinking among the chiefs here is to continue with the same basic mode, but simply upgrade the hardware, and leave the housing, connections, and maintainence to Derek, giving him some financial assistance.
I would highly recommend a dedicated server solution via a hosting company, instead.
You are going to get better value for your money. In addition, you take much of the work load off of someone like Derek, who would no longer have to house the server in his home, support/repair the server, support the high speed connection, etc.
In addition, by going the hosting route, good hosts have multiple redundant broad-band connections to the Internet.
The cost will be competitive or better than purchasing equipment and assuming the financial burden of self-maintaining it.
In situations like this, I think back to the Florida hurricanes -- through absolutely no fault on Derek's part, the entire system was down for days. While commerical hosts cannot insure that such an event could not happen to them, they usually are much better prepared, with things like redundant connections and backup generators, to survive such events.
If I were making this decision, I would think about the long-term stability and survivability of the site. I would stay away from a solution that is dependent for its operation on any one individual, even someone as reliable and sterling as Derek!
Good Luck, and please keep us informed.