The short version is I don't need another tablet, but I'm a horrible gear fiend so I'll probably get a Sheild2 when it's released just because it's hot, fresh, and new.
The processor on the Nexus 9 is extremely fast, and the huge screen is great for showing people what I can see and not see.
Before I make any changes though I really need to go fly with with my Project Tango tablet, which is really a Shield on steroids (Nvidia K1 processor, 4GB RAM) and LTE. That is what I'll be testing for Youtube streaming with.