Non-composite SIMMs can be fully utilized. The DOS Compatibility Card uses 72-pin, 80 ns or faster, non-composite SIMMs. Thus, if the correct SIMMs are used, the DOS Compatibility Card should be able to utilize the full capactiy of the memory.
Apple SIMMs are non-composite. Contact the manufacturer or vendor of the SIMM to determine whether any added SIMMs are composite or non-composite.