I remixed a thingiverse design by HEJHEJ of a hampster disc for my son Wylder’s degu.
Here is my remix: http://www.thingiverse.com/thing:272884
It uses a skateboard bearing, & it was a damn tight fit for my Form 1!
I’m impressed those spikes at the top half of the disc printed without supports. I figured overhangs like that would need them.
It depends on the angle, the size/weight of the feature, and the peel force on the print. But yes for a very large print that just barely fits in the build area it uses very little support! I’ve printed it twice and both had excellent spikes but on both the rear post was disconnected. But it printed, I just had to superglue it on.
Hey my Degu Disc made it into the Formlabs blog!
Winning! 
lol