The DR800SG is advertised as having fast page turns, and MobileTechReview's
IREX DR800SG review confirms that it is faster than the Nook.
The only way to tell for sure is side by side comparison of two devices on the same ePub. The 5" Hanlin V5 is only about 25% faster than the 6" Hanlin V3 for example, even though the former has 2x the cpu speed and a newer display controller.
The nearest 6" competitor to the DR800SG is the Onyx Boox 60 (Bebook Neo). This is certainly worth considering.