Can You Mix DDR3 Memory Latencies?

Hi, I'm looking to add some more RAM to my PC and I've read that you can mix different brands without any problems. I currently have 2x2GB G.Skill Ripjaws and the site that I ordered my current RAM no longer sells G.Skill. The RAM I am looking at has the same specs except for the latencies and voltage. Or, could I instead add 2 higher capacity sticks with the same specs to go with the two 2gb sticks, so I would have 2x2gb and 2x4gb?

Also, what is the "2N" in the CAS Latency? The other two sets do not have them at the end.

Current RAM: : G.Skill Ripjaws
Capacity ---------- 4GB (2GBx2)
System Type ------ DDR3
CAS Latency ------ 9-9-9-24-2N
Speed ------------ DDR3-1600 (PC3 12800)
Test Voltage ------ 1.5 Volts
Type ------------- 240-pin DIMM


New RAM: : Crucial Ballistix
Capacity ---------- 4GB (2GBx2)
System Type ------ DDR3
CAS Latency ------ 8-8-8-24
Speed ------------ DDR3-1600 (PC3 12800)
Test Voltage ------ 1.65 Volts
Type ------------- 240-pin DIMM

or

New RAM: : Corsair Dominator
Capacity ---------- 4GB (2GBx2)
System Type ------ DDR3
CAS Latency ------ 9-9-9-24
Speed ------------ DDR3-1600 (PC3 12800)
Test Voltage ------ 1.65 Volts
Type ------------- 240-pin DIMM


Thanks =)