I am new at this, but from what I experiencing from my setups:
Every rock are SAME. Just only the shapes and hickhike problems.
- Shapes: your choice, no comment, but RC and the one on 16 has more nicer shapes for display.
- Hickhike: any rock does have some with always. But I do have problems with G*ld Aquarium LR which are in my spare tank for more than a month now. the LR I bought from RC are in my main tank now and they are doing great as no bad hickhikers found YET only 1 of the very cool urchin and some cool starfishes found.
I dont really know about rest of those store in Calgary.

I am very sorry if this opinion is offensed to any vendor, but truly it is from what I've been thru with headages brought even into bed those night.