Just wider at the wings. I have been on all 3 saddles you mentioned. I hated the romin, the 143 power was almost great and the 155 power is what is on all my bikes now. Though I would love to try one of the new power saddles that have a small support layer for the tt bike (I know it’s a women’s but I think it would fix the small gripe I have with the one I currently have).
https://www.specialized.com/...?color=239333-159128

Thanks! Think I might have to try out a 155. Do you find yourself sitting on the back or just in front of the wings? Yeah, I've been looking into the Mimic version too. Looks interesting.

I am a 143 on the Power and a 155 on the Power ARC. The power has the wings more horizontal, whereas the ARC wings dive a little more.
This creates a larger perch area on the power vs. the ARC, so the 155 ARC was better.
I had to switch to the ARC after the power was rubbing the top of my hamstrings just a little too much. The ARC is just perfect, but YMMV as with any saddle suggestion.

I sit back up on the wings for sure. If I get too far forward too much soft tissue come through the cutout, hence the mimic.

I measure less than 143, but I could never make the 143 Power or Romin Evo work (for my road bike)......until i tried a 155 in both the Power and the Romin Evo. I ended up with the 155 Romin Evo. The 155 kept my sit bones stable and there was enough cut out for my hamstrings. The Romin Evo has enough room to shift around fore and aft, where the Power keeps you in one position. Basically the Power is a stub nose version of the Romin Evo. I found the the extra length works well for climbing, back of saddle, or riding the drops on the flats where you may find yourself creeping forward.

That's a really interesting point you make and I never thought about that. I was on the 143 Power and had the same hamstring issue which lead me to switch to the Arc. Think i might pick up an Arc 155 this week and check out the difference.

Thanks!