On Jan 10th I'm off to LAS. Here's the routing

BTV-ORD-LAS

The return is different

LAS-ORD-IAD-BTV

I had a schedule change on the return. I called and was told that the original flight from IAD to BTV has been cancelled and the next one would be 4 hours later. I asked the CSR what could be done about it and she putted the 4 of us direct between ORD-BTV. So, we'll arrive 6 hours ahead of the revised schedule! SO I would say it's worth it to call!!