In my experience they will not be major competitors for LMB forage. The Warmouth abundance too low if LMB present. Also Warmouth will target forage at size that appears to be prior to typical bottleneck for forage fish feeding into LMB.
A few years back I sat up a quarry where Warmouth were to be the top predator. Prey were RES, Pumpkinseed, Lake Chubsuckers, Red-fish Shiner, and Brook Silversides. Worked for three years until a yahoo messed it up. Still an interesting population although Green Sunfish and Bluegill are displacing others to varying degrees. Green Sunfish rule open water like a LMB while Warmouth dominate structure. For a while some of the Warmouth appeared to be approaching the state record.
Something interesting in Warmouth social behavior. I do not think they should be lumped in with other panfish type sunfish. To me they are somehow intermediate between Lepomis spp. and the black basses Micropterus spp. That is partly because of hybridizing experiments, not just looks and behavior.
