In most cases, 200mhz won't be noticeable, unless you are utilizing the memory for large files or renderings. In that case, the difference will be aggregate over the length of time. If you're planning to use the new build for a general workstation, gaming, and maybe some lite photoshop/video editing, go with the kit that best fits your budget, space constraints (if any), and look appeal.
We do also offer Vengeance RGB in 3200mhz if you are hard set on that frequency.