As I look, the lowest price you can get UD3H is $139, and D3H is $129. For $10 the UD3H offers better connectivity, (more SATA 3 ports, more flexible RAID options, and an extra PCIe 3.0 slot*) support for faster memory - up to 2666 Mhz and a couple more USB ports. That plus the overclockers'/enthusiast features like a dual bios switch and onboard power and reset buttons would be worth it TO ME. YMMV
* - It's not really an 'extra' slot. Both boards have 16X, 8X and 4X PCIe slots. The difference is that they are 3.0, 3.0 2.0 on the UD3h and 3.0, 2.0, 2.0 on the D3h.