Here's my two cents....
I sell both the WK1630 and the CTK671. Squeek is right, the CTK sounds better but the WK1630 has the 76 keys. My first choice in this price range though is the new Yamaha DGX202. It has 76 keys, a new "live" grand piano, better speakers, a dial data entry mode like the PSR550 and the PSR2000 plus keypad and inc./dec. buttons. It has very good styles compared to the Casio and it costs the same $299.00. This is an improved version of the very successful PSRGX76 which has been discontinued for the new model. Try one out........or try the new DGX300,which has 76 piano looking light weighted keys, a disk drive, good piano sound for around $449.00. Both of the Yamaha models are very light weight.
George Kaye
Kaye's Music Scene
Reseda, California