From what I've read online, Conventional is harder to qualify for and the DTI is stricter but if you can qualify, it's definitely the way to go. You don't want do have to pay 5 years of PMI if you don't have to.
I'm an S-Corp so figuring out my income was a little different (and actually very easy in the end...W2 income + K1 income + depreciation)
Take a look at the Form 1084 and you should be able to figure out what your income is for 24 months based on 2010 and 2011 taxes:
Your credit sounds great, no debt, you have a decent down payment, things should be pretty easy. Make sure the money you plan to use for the down payment is in the bank and it's been in there for at least 2 months, they don't like "mattress money". Also, make sure you don't have any NSF (insufficient funds fees) on your statements. I think if you have everything in place, which it sounds like you do, it's pretty smooth sailing.