Does the Vengeance memory have large hair combs glued to it?
Doesn't matter, get the Vengeance anyway. It not worth paying for the faster frequency of the Ripjaws RAM. Above 1600Mhz, there is little performance gain except for some situations (APU's), most of which is countered by the slower latencies (CL9 vs 11) and often higher voltages needed to achieve it.
However if its possible to get the Vengeance Low Profile RAM, without the large heatspreader, that would be ideal. Vengeance RAM can get in the way of large CPU heatsinks.
I'm too much of a computer nerd, I could tell all that just by looking at the product number...