That's kinda my issue right now zilla. I was going to get rid of my 4850 512MB and go with a 1GB 4870 just a few weeks prior to the launch of the 5000 series cards.
Now with the new cards coming out and since the 5770 is roughly equal to or greater than (depends on the game/app) the 4870 my thought has since changed. Both cards have 1GB of memory, however the 4870 uses FAR more power than the 5770 which is
extremely important to me as I strive to make my systems run on as little voltage as possible (every component). The 5770 is also quieter as it runs cooler so you can knock the fan speed down even further. It has the Eyefinity support which the 4870 does not, it has DX11 support which the 4870 does not, and it's smaller to boot.
Of course the DX11 part is just a bonus as I may never even use it anyway. The only thing I really use my machine for graphically is iRacing, and my 4850 pretty much has that covered except in the most extreme of circumstances. I run it at 1360*768 (32" LCD monitor@ 720p) with full options enabled and I get 60fps everywhere except for a certain track or two where I have to turn down an option or two, that or in replays if I have a field of 30 cars and full everything my fps will drop momentarily to 45-50fps until a few things clear out.
That is one of the reasons I was only looking to go up to the 4870 in the first place and the 1GB would help a little when 30 cars are on screen with every option enabled.
If you look at the same charts from Guru3d you'll see that what I'm looking at is the performance between the 4850 and the 4870 much like everyone else was when those two cards were new. Despite the fact that the performance isn't a huge gap between them, it's still significant enough that MANY people chose the 4870 over the 4850 when the single board cards came out.
Putting it into perspective, the 5770 and 4870 1GB models are almost exactly equal (one beats the other depending on the game), and you see why I'm thinking about getting the 5770. I don't play Crysis nor any other game on my machine anymore and haven't for probably over a year now. The massive extra power the 5850 makes for me is wasted totally, and while under load it will use more power than the 5770.
Hopefully that makes more sense as to my crazy thinking and why I was even entertaining a "competition" between the 5770 and 5850 cards. Obvioiusly a 5850 is far more powerful, but it's power I don't really need and may not for a long time. I'm just trying to figure out if paying for it now is better than paying for it later.
Rough number comparison...(4850 512MB vs. 5770 1GB)
Far Cry2
4850 = 18
5770 = 32
Dawn of Discovery
4850 = 24
5770 = 51
Call of Duty5
4850 = 43
5770 = 46
Crysis Warhead
4850 = 20
5770 = 26
Mass Effect
4850 = 47
5770 = 60
Fallout 3
4850 = 37
5770 = 50
Brother In Arms HH
4850 = 47
5770 = 63
Those are all from the same guru3d review that you posted. I know the 5770 is roughly the 4870 performance, but I don't think buying a 4870 instead of the 5770 is smarter for the other benefits you get with the 5770. Adding to that being on the first very early set of drivers, and the 5770 may yet get a bit more performance as time goes on.
Anything I missed that you think would help me further decide?
Kei