I have not thought about tube rolling. I have done SO much of that in the past that I have hundreds of tubes in various boxes around my house and to be honest I hope those days are over. I will evaluate the unit based on whatever tubes it comes with and if it doesn't do what I need it to do, it will be returned.
I use a CAPS v3 server as it allows me to use JRemote (the most amazing app). That said, if there's a sonic advantage of using the Aurender over a windows box, I might consider it, but the app would have to be really good...
If you have a ready available tube stash, you owe it to yourslef to try. This is not like amp tube rolling as you can change the DHT really on the fly and turn down the volume and change the rectis (almost on the fly). This tubes will last forever as they are not stressed by mere Dcac fuynctionality, given they are built for POWER amp duties. Find what you like best and stick with it. YOU HAVE THE TUBES already.