It really depends on the user. If you can't achieve the realism with P7, chances are that you will not be able to do it with P8 either. Even though IDL if you learn how to use it, may enhance realism in your renders, but the key word is learn. IDL is not a one stop solution, you will need to invest time into it to get the best out of it.

So far, still the best realistic images shown in the galleries have not made use of IDL.

Moving from P7 to P8 will not enhance realism, unless you're willing to spent a lot of time learning the ins and outs of IDL.

Artwork and 3DToons items, create the perfect place for you toon and other figures!

http://www.renderosity.com/mod/bcs/index.php?vendor=23722

Due to the childish TOS changes, I'm not allowed to link to my other products outside of Rendo anymore :(

Food for thought.....
https://www.youtube.com/watch?v=pYZw0dfLmLk