Basically none of us have control over who ultimately services our loans. I have three currently and each has changed hands at least two times. Two are currently with Bank of America and one is with Citi. Customer service is always tough on the servicing end - most staffs seem to be overwhelmed with call volume and/or lacking in knowledge.
I'm not sure if I have truly answered your question to your satisfaction but over the last 20 years I have offered to do conference calls with my customers to help with servicing issues. One other tidbit of information - most companies that outsource servicing to other countries will allow you to request to speak with someone from the US when you are on the phone with them. I know it's a small bit of help but hopefully it will be of some suport.
Inevitably most of the servicing of loans is going to be done by a few very large institutions. I don't like it either.
Some have better customer service than others, but none are perfect. Getting the right rate and term.... delivery and overall advice is far more important and impactful to you than who ends up servicing the loan.
Also, I'd ask how long it takes to close transactions and whether the rate can be locked for a long enough period to honor the initial terms offered.