I have no statistical basis for this, but as you know by now, I'm never reluctant to pass along my un-varnished opinion.
In my 21 years as a Georgia community banker, I've learned that the people & companies who truly succeed are those who provide consistently superior service by sweating the small details. Those who either can't or won't do what's right always resort to 'purchasing' customer loyalty with expensive gifts. It's the same as the non-custodial parent who's compelled to buy big-ticket toys for the child they lost custody of. In the end, you can buy neither love nor loyalty.
Relatively inexpensive tokens of appreciation are one of the crucial details that turn customers into raving fans (It's the thought that counts).
When I'm the customer (i.e. of a real estate closing attorney, etc), receiving front row tickets to a ball game leads me to assume that there was too much margin there. I'd much rather have paid less for the service & skipped the ball game.
As a case in point, next time you eat at Chick-fil-A, try saying "thank you" to any employee in the building. If the response isn't an enthusiastic "My pleasure", I'll buy you a chicken sandwich next Sunday. (Obviously I'm pretty confident about this. Chick-fil-A ain't open on Sundays.)
Again, this is my opinion, which is usually somewhere way past the right field foul pole.