While I'm not in love with that lineup, I think there's a strong case to be made right now that (especially if Baby's back) that 5 of our top 8 players (who are healthy) are 4/5s. Given that point, it certainly would be worth giving some big lineups some test runs.
While such lineups may be not be ideal, neither is any lineup that includes J.R. Giddens or Bill Walker. It's also not ideal playing Ray and Tony 48 mpg. And let's also remember, while KG or Baby might have to guard quicker 3s, smaller 3s will also have to guard them, so it goes both ways.
I say give it a try and see what happens.