Egrady, my system is all ARC, so your thread resonates with me. I agree that the only sensible way to break into the ARC product line is to buy used. That's the main way I acquired my ARC stuff.
The other way is to buy factory refurb units. The principal advantage is I know the unit is in tip top shape coming direct from ARC after a road show or whatever. Just picked up my "refurbed" PH-8 phono pre that way. Only problem going the refurb route is that you get only 15% off regular retail and you have to buy through a retail dealer, which to my mind is still not enough off and is inconvenient.
I don't know who ARC reaches out to with new products. If its the same customers who suffer from "upgrade-itis," I don't know if the "upgrade at cost" model will work for ARC because that would turn it into an "upgrade" shop which could limit profit margins. But . . . if ARC is penetrating the market by reaching new customers who are willing to pay full freight retail, then your suggestion would be be a nice courtesy to loyal "family members" like me.
A case in point is that I bought a used Ref 5 about a year or so ago. Shortly thereafter, the Ref 5 SE hit the market. The retal cost delta is $1000. However the cost for me to upgrade my Ref 5 is $2500! Now . . . as a member of the family so to speak, I would be really grateful if the upgrade cost was at cost to ARC. Maybe it is??? Who knows. Cal told me that the old Ref 5 version has to be practically remanufactured in order to bump it to SE grade.
Next to last point. The new SE version is touted to be in "another league" as compared to the "regular" Ref 5 version. Maybe it is. But I'll let you folks in on a little secret. I used to own the Ref 3 and PH-7 phono pre. Each was touted as a "major" improvement over its predecessor. IMHO, I would say that the improvement delta is measurable in the "tweak" magnitude sense -- not "in another league" magnitude.
Last few points. I just saw a used Ref 150 amp hitting the market. The ask price is $9K, which is $4K less than retail. Maybe I'll upgrade my VS-115 amp to a Ref 150 in a while, but not yet. I think my next change may be speakers, so I read member comments and learn and have some ideas. Maybe RSL ESLs (a Ralph Karsten "fave"); maybe Wilsons; maybe Magicos. Dunno yet. No rush. I'm kinda happy with my curent rig, so I will "stick" for a bit.