Well, I run an Asus A8N-SLI Deluxe at the moment. I found that getting the board to work "properly" required research, a BIOS upgrade, and changing some of the BIOS default settings that weren't quite right.
Having more BIOS settings does not necessarily make a motherboard more difficult to setup; having incorrect default BIOS settings does ...
From what I have read, DFI boards set up the easiest of all the nF4 boards because most, if not all, their default BIOS settings are bang on.
However, I believe almost any SLI board you buy will require a BIOS upgrade because the BIOSes and their settings are still being "tweaked".
I have built a dozen or so PCs, so far, and my next motherboard (for my FX57 CPU) will definitely be a DFI LanParty. I have not decided on the SLI-DR or the SLI-D yet because I do not use the SIL3114 SATA chip on my Asus board now (it's too slow and does not support NCQ) so I probably won't use the SIL chip on any future boards.
I think your choice might also be biased by cost, which affects all of us, and all the DFI SLI boards are selling at premium prices right now.
Maybe it would be better to wait a bit before upgrading your system, because you will probably have to buy a "not cheap either" power supply if your current PSU does NOT have a 24-pin motherboard connector and the requisite 6-pin PCIe graphics card connector(s).
I run a PC Power & Cooling 510W SLI which is one of the PSUs nVidia recommends for running two 6800 Ultras. Its cost is more than the cost of the MSI board you are thinking of buying.
Another reason for buying a DFI is that its components support the higher voltages some of the very fast VX memory sticks require. For example, running DDR550 memory as a stock, not OC'd, configuration can be done only with a DFI board. With any other SLI board, that kind of memory would be treated as an OC and might need modifications to the board or to the DIMM slots on the board.
If you don't upgrade often, and a motherboard has to last you for a while, then the DFI has more "headroom" to grow into than any of the other motherboards ... at this time. Yet another reason to proceed slowly.