At the money you would have saved, no.
You wished you gotten a R9 270/x
The prices for them are down by A LOT right now and the 7870 GHz editions are on sale every now and then for $140 after MIR. Better than the opposition Nvidia deal/cards by almost $100+.
If you just play games then yeah, 4GB. But if you like to multi task like a m******** and do a lot of strenous CAD stuff (or editing of media), then, you will want the 8GB. Someone I know, loves to play games in windows mode and leave them open, have Twitch Streaming in the background, multiple windows of a web browser (that schiit gets big), while skyping 24/7 on his laptop....and with photoshop and what not open to draw. If you are that guy, 4GB's isn't enough.