Filter w/ Lens Hood on Sigma 10-20

My Sigma 10-20mm lens arrived yesterday and it comes with a lens hood which I will use. I am wondering about using a UV filter with the lens hood. I know there have been many discussions here about the value of keeping a UV filter on the lens permanently for "protection" and one camp says yes and the other no. Suffice it too say that I have been in the yes camp.

Until now. With the hood on when using the lens and the lens cap on when the hood is reversed for storage, I don't see the need. And the person I talked to at the local camera shop said I run the risk of vignetting with both a filter and hood. He ended up saying "try it and see what happens." Well I don't know that I want to spend $80 for a 77mm UV filter to "try it and see what happens".

What do you think? Just use the hood and cap or go for the filter as added protection. I can think of an analogy when it comes to protection but we won't go there! :o

Where's the hood on the Sigma attach? If it threads onto the filter rings you might have an increased vigneting risk from stacking the two. If it attaches independently to the barrel (and that's what appears to be the case from Sigma's web site), the hood won't affect whether the filter causes vignetting or not, and using a slim UV filter should be just fine.

I'll note that I use filters whenever possible.