I bought a set of Artillian extensions as soon as Chris announced them. I bought them for two reasons: 1 - The 54 blade is far too small for a 2320 and 2 - I knew if it was a product that Chris designed and marketed that it would be good.
Installation was easy. Hardest part was drilling the holes in the blade. I did have to grind a bit off of the tab that fits in the reinforcement on the bottom of the blade. This will be my third year using them. I have a browntop driveway and keep the blade up an inch off of the surface, so wear is not an issue on the extensions. The flex in the rubber is beneficial in the event one hits a rock or other obstacle. I really don't foresee ever having to replace them.
Having said all of the above, I think if I did have to replace them, I would go with the steel extensions that John Deere makes. If money were no object I would replace the 54 blade with a 66 inch blade from Compact Tractor Attachments. The CTA blade is higher with more curve in the moldboard and would make my winter life much easier.
I'll continue to use what I have and think of Chris every time I look down at the extensions that he designed. If I'm not mistaken the price has increased considerable since I bought mine.