Many players will undoubtedly want to upgrade to this new revised streamlined version, i know I do. I hated the combat system of the 3rd edition and always use the Dice roll mechanic.
Many players also want this game to support more than 4 players too.
I think with the new revised edition there is a way, and it' means you can keep your old version.
the new version has spoiled a card that isn't in the current edition so there well may be other new cards in the game so buying the revised edition will give you new cards new mechanics and an extra board and tiles etc.
My idea is to put the boards old and new, which should be the same, side by side so that the stairs to the entryways join. The new optional rule of moving to any entryway from any entry way means you can now field up to 8 players moving across boards via the entryways.
You could put all the decks together or keep them separate, use one sun track or use both having 2 stages ie 2 days, with a penalty after day one, one as day and one as night. you can have two separate dragon chambers or have them both be the same room from which you can go to any board (thematically teleporting between chambers or have them as different levels of the same chamber).
the catacombs can now spread under both boards meaning you could go on and on and not 'crash' into the wall so easily
I think there is value in keeping your old game and buying the new one.