DDR2 isn't big for AMD as it is for Intel. AMD uses the Less Latency approach, while Intel uses the More Bandwidth approach. At the moment there is no real performance gain from going to DDR2 because of the added Latency that DDR2 modules must have to function properly.
DDR2 is worthless right now, except it may be better for Intel, either that or Intel just wants to boast new features.
SLI is a different story, but I wouldn't get it now either because I've noticed many people having trouble with SLI working properly. IMO, SLI just has too many issues to be something at this time.
I don't think SLI will be coming to SFF any time soon, if it does at all.