The two answers by Snipe and ewest provide good insight to your LMB-SMB questions. As Snipe says when you have BG you need LMB to keep BG from overpopulating. ewest has written a couple very good articles in PBoss magazine about catchability of LMB and them becoming hook shy. I agree with both member's conclusions. Hook smart - shy LMB characteristic has been discussed extensively in the past by PB forum members. LMB seem to have varying degrees of conditioning (smartness) regarding hook smart some willing bite lures others never bite lures. It is a distinct and common problem in small ponds with bass and even catfish. See topics in the Archives Common Pond Q&A section of about growing and managing LMB.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=255372#Post255372 When you get rid of the LMB or significantly reduce them then BG being very prolific become a major overpopulation problem. The overabundance of BG with SMB discussions have been dealt with here in the past by several members. It is a labor intensive management issue. Trying to catch all the LMB is very difficult. You can fairly easily remove 80% to 95% of the LMB but as you remove the majority the remaining smart LMB become conditioned to seeing their co-horts struggling as they are removed, then those remaining smart bass become 'smarter' more hook shy and only the most finesse and creative anglers can get the last smarties to bite a hook.
I think your best, most successful, and least frustrating plan is to remove some LMB maybe 20-40% as mainly to allow more or ample food for the SMB to grow well. Then treat the SMB as bonus fish and periodically add several (ladder stock) 10"-12" SMB annually to build and maintain SMB numbers.
Now if you are really serious about loving and having a high quality SMB dominated fishery then bite the bullet and completely renovate your pond and restock it with your forage - panfish - SMB combination. Once renovated it only takes a couple years to grow quality SMB to catchable sizes when they have the proper forage food base.
