https://www.solarblvd.com/product_info.php?products_id=3065 Any link to the voltages and times in the stages of the fixed charging profile?
the Eco-worthy 20 amp MPPT (for about $102 US) has adjustable voltages, but has only 50v Voc input limit while this Outback has 100v.
Also, just to argue :) , the Morningstar 15L has clipped amps at 15 so how much time in the (mid)day will it matter if the 20 amper can fully use a bigger array than the 15 could? You would have to do some sort of scenario with numbers for the daily AH haul comparison.
That ASSumes you do have a big enough array that would need the 20 amper for full amps but would go over the 15 amps part of the time.