Just a thought: If you are considering the AMS2 unit, something to consider. Yes it does have a much better design overall than the original AMS (easier to work on and trouble shoot and dries filament) but the drying feature only works when you are not printing. So for hours, the AMS is not available.
This Sunlu heating top can be added to the original AMS unit, I bought two of them. They are about $120 each. You can have them heat when the AMS unit is being used.