It depends on how skilled you are with SHAKE, and what your traditional colorist approach has been developed. No balls and knobs in SHAKE.
COLOR is way way faster as a grading tool, because that is what it is. On the other hand, its a terrible compositing tool... it is sometimes problematic to set up node trees... but plate work, it doesn't do at all.
I have tweaked elements in Shake, but it leaves a great deal to be desired in terms of subtlety and I would not attempt to grade a show through it. No way. HOwever, it remains a fantastic VFX platform.
Admittedly there is some overlap, but really, pretty marginal if you know what the strengths of each are.
jPo