I finally had a few minutes free today and downloaded and installed Epson Colorbase, their linearization software for the 48/78/9800 printers.
Without writing a full review, be advised that I realized it had some shortcomings for my uses right out of the gate: the main one being it can only be used with Epson media... So if you have a favorite non-Epson paper as I do, this tool will not add much value.
But, since I also use Epson's Premium Luster 250 on occasion, and since I happened to have a roll loaded in my 7800, I thought I'd go ahead and test out the linearization process. I followed the wizard and printed the small test target. Then after an approximate 30 minutes of drydown time -- the software prevents you from proceeding until the print has dried down -- I read the target with my i1. I then printed my standard test print with the linearization activated and printed a second copy with the new linearization turned off.
The net result for me was I saw virtually no difference between the two prints.
My opinion is that this tool has potential for anybody who prints primarily on Epson media, or anyone who has multiple (supported) Epson printers AND primarily uses Epson media and wants to keep those printers all in synch while using said Epson media.
It could be a superior tool if it allowed one to spec and use ANY paper.
***Note: My next thought was to go ahead and try to read a non-epson paper and generate a linearization while trying to trick the printer by selecting the similar Epson media -- similar to what we do when creating a dedicated profile for a third-party paper. I printed this target on the new paper per the above but at the reading process got an "out of gamut" error telling me the target was unusable and to reprint another. Apparently the software is smart enough to know what its own media base should look like and won't let you try and circumvent it.
So for me, it's back to using dedicated profiles.