Yes they are nice. I always become indecisive when it comes to assigning keys with keychord.

Also, Sticky keys are system-wide as it is an OS provided feature. It makes life very easy, for example, to select text, just click where you want to start selecting and go to end of your selection, tap shift and click mouse, selected. I wish more people give it a chance.

Keychords are a bit of a pain in the ass if you type quickly and want to have mnemonic shortcuts.