Outside of the Interest Rate & Basic Fees...Does It Really Matter Who the Lender Is??

I had a friendly disagreement with a family member over a loan he has applied for...I warned him about using this bank but I was told that he had shopped for the best fees and the mortgage broker told him that all lenders and underwriters have to do the same required documentation.  I strongly encouraged him to submit his packet to two different mortgage brokers and not to use the bank lender that he had chosen because I had heard many complaints. Again, he assured me that since January, underwriters have to use the same guidelines and the required documentation is the same so he didn't feel he would gain anything from doing twice the work.  Is this true?  I don't really know.  I am leasing not selling since December.  I am sure I will hear if there are issues; it will be interesting to see who is right?