You may be able to manually squeeze out different timings, but if your"results" are practical benchmarks; then no matter what you pick for timings you get at best 1-2% difference in real-world applications.
Since DDR3-1600 is natively supported on all modern processors it may be written as a JEDEC profile on some memory module rather than an XMP profile. Similarly, it is very common for DDR3-1600+ modules to put the DDR3-1600+ profiles in XMP even if they conform to the JEDEC standard.
The difference between the two is that the highest natively supported JEDEC profile will be selected automatically. XMP profiles will never be selected automatically and must be enabled manually in BIOS/EFI setup. XMP profiles may use non-standard timings and voltages, JEDEC profiles will always use standard timings and voltages.
Anyway, your DDR3-2133 modules will most likely contain the profile necessary to run at DDR3-1600 speeds which will make it identical to the second one that you listed.
Having higher clock capable RAM ensures that when you overclock, you have some room to play with on memory dividers and frequencies. Running it at 2133 even with an over clocked Ivy Bridge doesn't yield a lot of gains (very very small gains), see Tomshardware review: