"The 50 to 75 yard effective range would have made them not quite as effective as the .69 smoothbore of the time using Buck and Ball ammunition."

I would like to see that tested. Those 40 .45 cal balls would be coming pretty fast against a .69 smoothbore musket (whose hit rate was pretty poor). The known pump was awkward but effective. The compressed air cylinder was detachable- like the Army Revolver, where extra cylinders could be carried, the soldier could carry extra cylinders in a bag. Again, this would have added to the cost of the weapon to produce.