Connor,
I have been spending some time the last few months trying to get my arms around the "pellet trained fish do not do well on natural forage," statements.
Here is a thread I just started that you might find useful:
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=462452#Post462452FWIW my answer to your question is, with what I've learned so far, IMO I would go ahead and stock the 6 to 8 inch pellet trained LMB.
My rationale:
1)You feed pellets to your GSF and BG already so the LMB will not starve if they don't immediately attack the natural forage.
2) You have an abundance of appropriate forage with the smaller GSF and BG to support 6 to 8 inch LMB
3) There is little/no competition from existing "wild" LMB in your BOW although you probably have large enough GSF to compete in the beginning.
I still believe non-pellet trained LMB would be best in your situation where you are looking for a predator to cull smaller GSF to get you that trophy but, IMO, you have an excellent chance of achieving a good result with the pellet trained ones and their offspring.
I am not a pro, just my 1 cent....
Bill D.