OP, wouldn't Jester be a Jack as opposed to a Gainer, since you can choose who gets a copy of the revealed card (and if it's a victory card you don't gain anything)?
Woops, you're totally correct.
So, Farmland and Governor are Upgrading cards even though they do the same as Remodel? What you are try to differentiate is "Remodel"-type cards with and without the word "exactly", am I right? I agree that this makes a difference. But Rats has to be an Upgrader too then, because there is the possibility that there are no Rats available anymore. And even though this almost never happens, there might be edge-cases when even a up-to Remodel fails, for example if there are no Coppers and Silvers left, Mine fails too.
Farmland and Governor (thank you I missed that one) require and exactly $2 better card, and so don't do quite the same as remodel.
Also yes you're quite right; this is ignoring edge cases for the remodel style cards of running out the coppers and curses.
I agree with pretty much everything Qvist has said here, and I wonder at what you consider to be an edge case. Running out of Rats doesn't seem like that much of an edge case to me, for example. Trashing no cards with Forge is also an edge case, which would thus disqualify it from your definition for "Developer".
Also, shouldn't Transmute be a Develop by your definitions? You can gain two cards with it by trashing Great Hall, Island, Nobles or Harem.
In general, looking at whether the card will leave you with more or fewer cards isn't that helpful. I think Qvist's classes are much more useful.
Yeah I actually agree that Trash for Benefit vs Pure Trash is a very helpful way to think about these cards. I was just trying to look at things in a different sense. More about the trend of total cards in your deck vs the total quality. Basically you're always trying to make your deck better quality right? You can think about your average deck quality (q) as overall quality (Q) divided by the total number of cards (c) q=Q/c. Trashers reduce c thus improving q. Gainers increase Q, thus improving q. Remodels both reduce c and increase Q, thereby increasing q.
I find the middle ground cards interesting. The gainers and sometimes trash, and the trashers that sometimes gain. If you play a lot of Remakes for example your deck size is unlikely to stay exactly the same size, you'll trash some coppers permanently sending it down. So you should think of Remakes in a different category to Remodel. Hermit will gain you silvers, but it will sometimes let you trash; thus you should think of it differently to workshop (and similarly to Jack).
Also you're right about the edge cases. Pilling the rats is quite a common one. I'll need to rethink how I deal with that.
It's making me a better scientist.