I am actually thinking the darker would look better and the "live rock" holes sound awesome because I would be able to more easily anchor java moss to it...or so is my postulation. I was thinking that crushed shells would cause problems with the water chemistry. Thanks for the help!
EDIT: Since I don't want to clutter this thread and couldn't find anything with the search I started my own thread. Here is the link
if anyone has any more comments without cluttering this thread. Thank you all for the help so far!