The 5K L.E, as the name suggests is a limited edition version of the 5K. The big selling point of the 5k L.E is the next generation gaming-grade laser sensor hailing from the halls of Avago - the A9800. The new laser allows a ridiculously high DPI of 8200 CPI capable of delivering a sample rate of 12000 fps. Not the highest we have sampled I grant you. The SteelSeries Sensei delivered an effective 11400 CPI however this CPI was achieved by the on-board ARM processor meaning the Sensei's physical limit was in fact 5700 CPI. The QPAD 5K L.E betters this and hits a massive 8200 CPI without the need for additional processing. So while the QPAD has the highest physical CPI, the Sensei the highest theoretical CPI, the 5K L.E can hit it's CPI without degradation of accuracy and precision.
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips