Does it matter if I go with this lender or the other one?

Not all lenders are created equal.
There are, IMHO, 3 important parties to every transaction. Buyer, seller and the undervalued LENDER.
Most buyers think that process of buying a house is:  find a house, write an offer, offer gets accepted and with the help of their real estate agent, they take the right steps, get the loan and close the transaction and move in.
This scenario is only partly that simple. If you are getting a loan, there is a very important party to the game called "The Lender" who can VERY MUCH SO make or break the deal. And in this competitive market, a buyer just can't afford to have a weak player in his/her team.
Let me repeat myself because its a known fact among us in the business and an undervalued  one among those who are not. Lenders can and will  endanger/make/break a deal.
See, from the day an escrow is opened, until the day buyer gets the keys to the property, (normally 30-45 days ) there are timelines which everyone is supposed to meet or the deal is in jeopardy.
We real estate professional don't have a problem with anybody like buyers, sellers, inspectors,etc meeting their deadlines. But day in and day out we do have problem with lenders meeting their deadlines. Lenders have to order appraisal, etc and if they are not doing everything in a timely manner, seller can cancel or give the buyer a hard time if they choose to. My job is to consult the buyer in a way  to avoid that from happening.
During my career, I have worked with a handful of lenders and have chosen to work with some and not with others.
Here is a summery of what I have learned which I am sharing with you:
-A lender in Texas or New York whom I have not met, and I don't have a relationship with,doesnt really care to get repeat clients from me, the agent. He/she doesn't have to answer my phone calls or return my emails reminding him that the appraisal is not ordered yet and we are running late. The local loan officers I have picked to work with me, return calls/emails even on a Sunday afternoon. They want to work with me and for my clients ON A TIMELY MANNER  in order to get more referrals from me. They want to take care of my client and keep me happy so they get more referrals from me. 
-A lender who is juggling 30 files at a time, need to be reminded (by me, the buyer's agent) to do things they are supposed to do all the time. I prefer that that lender is local, nearby and someone whom I know and have dealt with before. I have no leverage with the lender whom my  buyer found online who is in Chicago. I hope I am making sense.
-A lender who is quoting a teaser low rate to the buyer to entice them to work with him/her, does exist. If days before escrow buyer finds out that what he was promised and what he is getting are two different rates, closing costs, there's nothing anybody can do. Local lender I work with simply doesn't  do that because they have to answer to ME.
Karen Dunn is such a local lender.  She has proven to be a great and caring loan officer time and time again. She won't disappoint.