Wow you posted the exact same thread I was going to. I too have both of them, and I only plan on using Wandy at home, so missing this start means a lot. I imagine a low-scoring game. I would start both of them, but I don't want to get any more loses. Besides I already lead my league in IP and K. If you are already doing well in IP and K then I would just start Billingsley. If you need IP and K and don't mind taking a loss, then start them both.
Personally, I'm not conservative, I go big in all my moves, and yes, i some of them were bad moves, but more of them were brilliant ones. If you want to win in your league, you gotta play like a high roller. I started Gollardo against Johan, Maholm against Florida, Weaver against Boston, and reaped the benefits. So, I guess what I'm trying to say is, always go with gut instinct, and stick with it. Gut instinct will help you more than hurt you, dont be deterred if your gut instinct let you down, just stick with it, and in the end itll have helped you a lot more than the conservative owners in your league.
Start Billingsley and bench the hot-streaking Wandy whos great at home. That's my gut instinct. You can always use Wandy in other outings, just bench him tommorow.