I've used the same broker on the last two houses I've bought. It is nice to have him available, as I've been working with him for five years and he is very responsive. It's also nice to log into one system to pay my mortgages, however; Sebonic is offering 3.6% with no lender fees (saves me about 1K) vs 4% and about 1K that my old broker is offering for closing fees.
The difference in payment over 30 years is about 46K with the difference between payment and principle, not counting interest I could earn on that money. On paper the better business decision is to go with the lower rate, and I'm certainly leaning in that direction, but is it?
I like the relationship I have with my old broker, and being able to log into one system to pay my mortgages, however, I don't think it's worth 46K+, as I can setup auto payment through the two different sites and not have to monitor directly (actually already setup for the two mortgages I have with my existing lender). Once the loan is in place, there doesn't seem to be that much difference in service, but there sure is a difference in money I keep in my pocket.