In 1997, I had the CTK-601. The rhythm numbers around 020 were the dance-orientated ones. I think 027 was trance and around 019/020 was a beat called very funky, written as VeryFnky as it was limited to 8 letters. Brilliant and syncopated beat! It also had a jungle beat which I liked. You could also change which drumkit they used. The best thing about this keyboard though is that you could go into synthesiser mode, pick 2 voices, alter them if you wished, then re-package them as a single voice and save it as a user voice. Think they were numbered 160+ after the drumkits. For saving music, I had a MIDI sequencer where you could save the files onto a floppy disk, a process known as data dump (or bulk dump). So yes, very fond memories of this keyboard.
Did anyone else have a CTK around 20 years ago? The '6' in 601 was the series number, then the numbers after the 6 would be just the country/region plus any extra options.
Afterwards, I had a WK-3500 (in 2005), a CTK-5000 (in 2010) and now I'm after an MZ-X500 although I can't seem to find any in the UK at the moment.