I love my yellow colony polops, and would never compare them to aptasia.
I have mine on their own rock towards the bottom of my tank
where the light isn't so strong, but water flow is good.
seems to give good balance to my tank and leaves the upper brighter areas for things that really need that intense light.
When they start to grow, and they will, just place a rock next to them to latch on to. My LFS loves to buy them or trade .
Good luck and enjoy your new buddies!