I don't know why a dealer would say the ACE27.1 is discontinued...it is listed on Thor's website for the 2015 line...maybe deserves a call to Thor to confirm what the dealer is saying.
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The ACE and Axis drive differences should be obvious. The ACE 27.1 and 29.2 are riding on a 16,000lb GVWR F53 RV chassis. The Axis is riding on a 12,500lb GVWR stripped E-Series chassis. Besides the obvious weight capability, the Axis has an independant front suspension (IFS) vs. the F53's solid beam axle. IFS should provide a noticeably better ride...just the nature of the design...but at the cost of weight capability.
It should be noticed that the Axis has no leveling jack system as standard equipment...a big deal if you camp away from campgrounds or lots with nice flat surfaces.
I would test drive both rigs to see the difference, which could be obvious.