Mixed Brands? OCZ & CORSAIR

When I built my i7 920 system I used this ram

http://www.newegg.com/Product/Product.aspx?Item=N82E16820227379

OCZ Reaper HPC DDR3 1866, 9-9-9-28 which I has been discontinued and isn't stocked anywhere that I would want to buy from. One place has some for 2x the cost of the corsair kit.

I am in need of upgrading and I'm thinking I can toss this ram in with it

http://www.newegg.com/Product/Product.aspx?Item=N82E16820145292

CORSAIR DOMINATOR GT DDR3 1866, 9-9-9-24

Granted my i7 is overclocked running 4.2ghz I can't remember off the top of my head what my ram is running at as it has been two years sense I setup the overclock.

My thinking is that because the ram is so similar in specs and the corsair in theory has slightly better timing it should be able to run whatever the ocz is running.

I figure if it comes down to it, I can buy another set of the corsair and use the ocz in another build. But it would be nice if it would "just work".

Thoughts?

I would just dump the OCZ, and instead of 2 x 6GB Corsair DDR3-1866 kits get this 12GB kit of G.Skill Pi series DDR3-1600...

G.SKILL PI Series 12GB (6 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL7T2-12GBPI
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231331

... rated at 7-8-7-24-2N and 1.5V for $199.00

I need to check when I get home but I want to say I'm running my ram faster then the OCZ is rated for, thus at the speeds they will need to run to keep my OC, I doubt that ram will be able to maintain faster timings then what I currently have. But I need to see what I'm running now for sure so I can make a more educated guess.

At 4.2GHz (210 BCLK x 20), if the RAM is at a higher frequency than its rated DDR3-1866, then it's currently at DDR3-2100 (x10 DRAM multiplier) w/ looser timings than the modules rated 9-9-9. You'd be better off w/ some good DDR3-1600 like the G.Skill I linked you to, and set the DRAM multiplier to x8 = DDR3-1680 at their rated 7-8-7-24 and 1.5V.

It is at ddr3-2xxx and running 9-9-9-24 now.

I've heard that tighter timings doesn't matter much on Intel cpu's like it does with AMD's? Forgive my ignorance, even though I've been overclocking stuff for years I still don't fully understand the effects of ram timing vs speed.