larger hoses are a no go. THey are too large for the solenoid.
The solenoid uses an approximately .100 opening (approximately because i do not know the exact size). Cocker hose is approx .0625 (1/16). Going any larger means that you're going to run into filling the volume inside the hose before being able to fire the gun (which means it takes longer to cycle). As to whetehr it would reduce pressure, i'm not quite sure. It's just not feasible to increase your dwell by a large margin to accomodate larger hoses, possibly decreasing your pressure.
The current high flow barbs are as big as they can be, without being structurally too weak. You do have to be careful installing them becuase they are a little weaker than stock ones.