Is the Aisin transmission worth it?

You need to consider what load you are carrying and how often. If you tow only on major holidays and otherwise use the vehicle for commuting or it sits in storage, you may not need the Aisin even though you may have a heavy load. We go out often April through October and are usually crossing mountains, so we have the Aisin. November through March we avoid towing through snowy mountain passes, but we still camp in the low lands and at sea level. We still have coastal ranges to cross, but these are easy compared to what we do during other parts of the year.