Justin's comments are spot on with the RTT and the Oztent. I've never owned a springbar.
I got rid of my eezi awn because I got tired of having to put away the tent if I wanted to drive anywhere. I found I wouldn't go places once camp was setup because I didn't want to put the tent away. I found it to be a pain to pack it up while on the roof of my 80. back and forth and up and down around the 80 to properly store the tent...
With the RV5, I have the peaked side panels and floor saver all packed in the RV5 carry case. It's a beast to put on the roof rack but still easier to lash down than the rtt. It does have a large footprint so that could become a limitation. But I love that it's a true living space. I can stand in it, and the patio provides nice shelter from the elements.
Now that I have a chaser, I'd like to put a rtt on it in addition to the rv5. I figure it'd be less cumbersome to open/close with it closer to the ground. It gives me options. The rtt would provide a comfy, fast setup sleeping quarter. I could keep a pillow and down comforter in there, so once it's open it's ready to go.