The new parameters disappear. Turn it back on, and let's look at each field. This is great for smooth, watery lead lines, and snaky basses. When Legato Play is set to OFF, an attack will be triggered with each new note. Portamento is a real throwback.
Synthesizers support two different rate types - equal time and set rate.
The K2000 supports set rate portamento, meaning that the sound will move a certain distance each second. Change this field to OFF, and check the sound of both legato and Staccato note runs. Switch it back on, and see the difference. Interesting, but nothing special. Now, play the same organ licks, only do them for about eight measures.