The mini post rubbers are MUCH bouncier than standard rubber. On Stern Star Trek, I put Super mini-posts in the outlane and it was as though I closed up the outlane because the ball would seemingly bounce completely clear of the outlane with even slow balls. It behaved as though I nudged the machine perfectly every time. It's opposite from Super Bands which some people critique for being too "dead".

They are as indestructible as the Super Bands.

I don't know when that happened, but he has indicated he would have built Star Trek with Super Bands and Super Mini Posts if he had known about them during game design. See item 6:
https://pinside.com/pinball/forum/topic/stern-star-trek-summary-of-fixes

I used Super Mini post rubbers on Stern Star Trek. I replaced all of them, approximately 18 in total.

In my experience, the super mini posts bounce much more than black rubbers or white rubbers. The extra bounce has the effect of making openings feel more narrow. For example, the ball more often bounces clear away from the outlanes. Also, the Vengeance gap feels more narrow.

I loved the extra bounce from the super posts, which is a marked difference from the reduced bounce of super bands.

I'm not sure why this would be a problem. Super Posts also have a flat side, but that does not pose a problem. (The flat side can be oriented facing down or up.) With rings, I don't see a problem with having a flat side facing out or in.

The Super Posts are extremely bouncy (more bouncy than white rubbers) and I love the increased bounce.

Ditto