I'm in the same boat. Great machine. Once the economy changes for the better (which at the rate we're going...) I will probably upgrade as well.
My shortlist is Esoteric X0-3, AR CD-7 (with upgraded power supply), Ayre CXe-5. I could be probably be persuaded to include a 306 Pro depending upon which way the wind is blowing that day.
One area that I'm disappointed in (which really doesn't have to do with the unit) is the dearth of HDCD titles. Seems like production has been lacking lately and artists that were using the medium (like Neil Young) are dropping it. The few new titles that you see are for the most part pretty obscure stuff you wouldn't want anyway.