After just going thru both processes, license renewal and TWIC card I can tell you this. As of now, neither group even recognizes each other. Homeland Security and Coast Guard do their own thing. No where in the license renewal process does it even mention TWIC cards(although it was excepted as a form of ID).
That may all change after April 15 ???? No one has a definite answer.
And John is right, our congress people are concerned with much greater thing right now than TWIC cards. I don't see it changing with their help.
Do what you think is right for you, but I wouldn't count on grace periods or lack of enforcement when it does go into effect.
These are just my opinions after dealing with both groups for a long time.
D.Brown Lake Ontario Charter Boat Association