Since 1980, Blacks have lived through 24 years of Republican Presidents and 20 years of Democratic Presidents. The fearmongering simply doesn't match history. I dare you to find me Republican legislation that was worse for Black people over this time frame than the Crime Bill, NAFTA, Welfare Reform, and Obama's Bank Bailout.
The Democratic party is more invested in White Suburban voters than blacks, so it doesn't matter how many D's you vote in, your interest as a Black American won't matter. As long as the DNC has you thinking you have no alternative, they don't have to listen to you. We just lived through a recent Democratic held Senate, House, and White House, yet no significant policy was passed. Remember, in Senate Reconciliation, as long as your party has a simple majority, the opposing party is helpless to fight your legislation (No filibuster). Again, your proposal struggles to reconcile with history.