If you could let us know what the rest of your setup is like, we'd be able to offer more specific advice. However...
I've got a cheap 270x that didn't overclock much (Powercolor TurboDuo), but it's more than capable of running
1080p at
40+ fps in recent titles (Metro Last Light, Ass Creed 3, FarCry 3, etc.) at
high settings and older ones at
Enthusiast/Gamer (Crysis, Metro 2033, FarCry 2) at
60+ fps. I don't buy the latest games, I just wait for them to become affordable!
3GB of VRAM will only become useful if you rock several monitors or have one over 1080p; if you can afford that setup, you can surely afford a better card!
The extra RAM is wasted at lower resolution, as it's only for textures and my 2GB is rarely troubled at 1080.
In the meantime, if you don't need more than 40 fps and are either:
a) going to upgrade the GPU in a year or two
b) add a second 270x in CrossFire later on
I reckon you should use the spare cash to buy a larger SSD or more RAM (or treat yourself to a beer in the knowledge you've saved some cash!). Or buy a 280x and up the ante...
That's my tuppence worth, let me know what you think, other commentards out there!
PS as part of your research, have a quick look through the Tom's articles about graphics cards, RAM usage and so on. My sweet spot (UK £120) was the 270x, as the frame rate didn't scale with price beyond that. nVidia cards are nice but more expensive...