FYI for anyone still wondering.... I just received this reply from HTC's VP of Product Management on Twitter. I asked him when the Sprint M7 will get 4.4.3. Looks like we get to wait for L.
"@TheRhob Hi Robert, we're going to go straight to L r...
Need few more to test and confirm to it roll out the update
My data seems to be working great now, shows 3g is connected. My SMS is still showing the sending notifications. Thanks for your work.