Thanks! Good answer too. It is good to know that some HTC One phones work well with CDMA. So I still have hope.
I'll go back to a different BestBuy store to exchange for another HTC One.
Something very interesting happened this morning. I got a Sprint Zone message requesting a software upgrade. It did not specify what the upgrade would do. But since it was from Sprint Zone, I clicked "ok". Then amazingly, I found the death grip problem went away!
Draw your own conclusion. :-) Thanks all for the help.