For the probable price/performance gain, I would say no. If I was going to wait for anything, it'd be longer term and the 50xx at this point.
If the only concern is gaming, generally I would say ... no. Except, perhaps, if you're one of those who likes to run a game with 500 mods and mega texture packs. Or, er, maybe if you like having 400 browser tabs open. Or if you constantly do specific non-game software/tasks that are extremely RAM heavy. But for general desktop/office/gaming concerns - nah, there's no need. Ram's also easy to add to or swap later. Well, typically, not familiar with Dell.