just my opinion... 

i use adjustments of bagginsbill's gamma corrected materials in P6.  i still make corrections in Photoshop.  in my experience, it's always better to get as good an initial result as possible.  and i'm probably just not knowledgeable enough, but i haven't been able to get as good results from just color correcting in post.

i'll research and see if i can learn enough to improve an old image and compare.