I've been ampless for years now. Not having an amp on stage has never affected the dynamics or the ability of the players to respond to subtle changes; in fact, those I regular play with would tend to agree that going ampless enhances each individual's ability to hear and respond to nuances given a customized mix without sonic clutter and mic bleed from amps on stage.
Once the levels are set in the monitors correctly, whether IEMs or wedges, you should be able to hear very subtle nuances from each player. The size of the venue, the number of songs played, the variety or type of music played nor the size of the band should matter; once the monitors are set properly everyone should be able to hear with clarity. If you can't then you either don't have enough monitor sends to give everyone their own mix or you have not clearly conveyed to whoever is mixing the monitors what you need. As noted above, if you have a digital board, there is no reason why you cannot run your own monitor mix off an ap on your phone.