It depends on the size and typical use of the system. If you are working it at high capacity for extended times you will probably notice voltage loss. Many installers do not ever include high output alternators with their installs. This may or may not cause problems with power verses demand.
If you are normally using the equipment at 30-40% of its capacity, which is pretty typical, the original alternator could possibly keep your voltage stable. The main thing is keeping your battery/s in good condition and after high use do not rely on the alternator to charge up discharged batteries. It should only be used to maintain the charge of a good battery while powering the car's electronics. If an alternator is ever used to charge up dead batteries or maintain weak batteries it will burn out. The battery stores an immense amount of current and an alternator will be damaged trying to work along side bad, weak or discharged batteries.
You will need to monitor the voltage with a meter while running at different RPM with the loads on. If the alternator falls and stays below 13.5 Volts, it is struggling to keep up with the demand, or a bad component or cables is causing a voltage drop. Either condition will prematurely damage the alternator also.
If you notice that at all desired loads at different RPMs you are in a good state of voltage (13.5-14.9V) with your original alternator, then you are good to keep the original. Always monitor that voltage to make sure in range. If you ignore an oil light you damage a motor, and if you ignore a bad voltage condition you damage batteries and possibly other electronics.
Good Luck!!