I had my Microwave XT for about 3 weeks. I had a month to decide if I wanted to keep it or return it to Guitar Center. The Microwave I bought had 10 voice polyphony. New Microwave XT's can be bought that have 30 voice polyphony. The 30 voice models will cost about $300 more than the 10 voice models. If you buy the 10 voice model thinking you will add the additional voices later, it will cost you $575 plus shipping to get the expansion installed by the Waldorf California Service Center. (The expansion is not user installable). In the limited time I had with the microwave Xt, I tried it out with various editor librarians. I recommend the Sound Tower Microwave2/XT editor. It saves single programs and multis very nicely and provides editing and saving of user wavetables as well. (By the way the microwave user wavetables are not nameable so it will be very tricky keeping track of them so don't get too excited about this feature of the Microwave). If you have Sound Diver, you can also store and edit and set up wavetables as well. I had less success with Soundquest's Midiquest editor librarian. I couldn't send Multis to the Microwave except one at a time . Soundtower comes with 9 banks of sounds in soundtower format so you will have to pay the $50 registration fee to be able to load them into your microwave. Since there were only about 3 other banks of sounds I could find on the Internet, (and none for sale otherwise) I recommend the investment in the Soundtower editor for PC Windows.
Soundtower also does probably the best editor for the Korg Wavestation series. I mention this because the Microwave XT does not sound much like a wavestation as it sweeps its wavetables rather than goes step wise through them. Namely, it interpolates the wave values and interconnects the waves to form a smooth sweep.
I returned my Microwave XT mainly because of the price involved in getting my Microwave XT to 30 voice status. BTW, the multis that would benefit from this treatment are often not included in any banks you can currently get (or just a dozen or so per bank so you will have to roll your own).
The Microwave XT can also receive in all midi channel Omni mode which makes it useful to me as a Midi guitarist. As far as the sound goes, it is unique and blended very well with my Oberheim Matrix 1000 so I will miss not having it. But since you can't name your own user wavetables, I will give it a 4.