Stick with GTX 260 (Core 216) or Get HD 5770?

No, the GTX260 is faster.
Do not worry about the HD5770s DX11 capabilities, from the tests I have seen and done the '5770 is not fast enough to use the new tech without suffering a huge performance hit.

Stick with that good card 

Thanks with the opinions, I will stick to it   Maybe get the 5850 and up when they get a little cheaper.

DX11 can actually bring about a performance increase, as there is better texture compression & lightning.

Link:
http://www.pcgameshardware.com/aid,700136/Stalker-Call-...

Average changes:

DX11 / DX9:
Day - 44/108 = .41 = 41% DX11 performs worse, 59% drop
Night - 38/119 = .32 = 32% DX11 performs worse, 68% drop
Rain - 41/128 = .32 = 32% DX11 performs worse, 68% drop
SunShafts - 29/54 = .54 = 54% DX11 performs worse, 46% drop

DX11/DX10:
Day - 44/38 = 1.16 = 116% DX11 performs better, 16% gain
Night - 38/33 = 1.15 = 115% DX11 performs better, 15% gain
Rain - 41/35 = 1.17 = 117% DX11 performs better, 17% gain
SunShafts - 29/27 = 1.07 = 107% DX11 performs better, 7% gain

DX11/DX10.1:
Day - 44/37 = 1.19 = 119% DX11 performs better, 19% gain
Night - 38/33 = 1.15 = 115% DX11 performs better, 15% gain
Rain - 41/34 = 1.21 = 121% DX11 performs better, 21% gain
SunShafts - 29/26 = 1.12 = 112% DX11 performs better, 12% gain



DX11 only performs worse than DX9 (around 60.25% worse), while being better than DX10 (13.75%), and DX10.1 (16.75%)

However, I would still stick with the GTX 260, just pointing out some facts.

I would just hang onto the GTX260 instead of a 5770. The new card won't be much of an upgrade and in some games will be a significant downgrade. However a 5850 or better then sure they wold be an upgrade.

Anyone know about comparison from GTX 260 core 216 vs 5770 XXX?

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

The GTX 260 will still be slightly superior.
The XXX card has only a minor 25Mhz core 25Mhz mem (100Mhz effective) overclock, not enough to make a major performance difference.

Regardless of any overclocks, the minimum you would need for a decent upgrade would be a 5850.
Anything less would give you similar, or worse, performance.