Technical superiority is pretty hard to debate against unless it has costs associated with it (and unless such costs happen to be higher than the costs of maintaining the old technology).
Fortunately for us, the cost of transition here has been laid out in the form of adaptation.The cost of holding on to W3D meanwhile is the dwindling player base and overall reduction in the form of a "return" on the time invested in this venture.
A transition to an engine as reputed, optimized and malleable as UDK would be of greater benefit to everyone involved in this community and would warrant in objective terms the temporal investment.
While an example such as RenX has its faults and deficiencies, but no one can argue about their progress and how much they've been able to achieve. Part of this comes from leadership and focus on their end, but the other part also comes from how easy playing with UDK is.
Modding for W3D is a struggle some of us are still willing to undertake out of pure sadomasochism.
I know it can be argued that potential maintenance issues in the long run will be alleviated the same way that technical problems with the old crop of WS RTS games have been addressed by the community repeatedly. However, as Aircraftkiller pointed out, we're extremely dependant on people that could decide to move on any day from now.
