Nigel,
The WK-3500 is working very well for me. I think I played this board more in that past few months than I did the entire time I owned the PSR-550 I'm just more inspired to play the Casio because of several things. I could not stand most of the bass guitars on the 550 especially the slap bass. The Casio has really good bass guitars, that I feel are better than the 550's. Also I could not live with the saxes on the 550. They had no bottem end and no punch. Sure the sweet tenor was nice, but there was no sax to really blow out a solo with. The WK-3500 saxes are (how should I say) mouth watering The velo tenor and velo alto are really nice. Plus the other saxes outside the velo ones are very strong. I truly love having 76 keys and having both pitchbend and modulation wheels. One feature that keeps me smiling is the ability to load new wave samples into the WK. If you know what you're doing you can get some nice voices in there Basically if I bought the PSR-3000 tomorrow I would still keep the WK-3500. You can't go wrong with this keybaord in your home. Many have complained about the limited sequencing tracks, and no style editing, but there are ways around that as well.... If I want to loop drum tracks I use my drum machine (besides, the drum machine is going to give you better drums anyways), and if I want to record a huge composition with more than 6 tracks I have software for that. Plus there are several FREE midi sequencing software programs on the web too.

Squeak