I own both P5K64 WS and Rampage Extreme so I can share what I learn so far 😀
Rampage isn't worth 300$ (I got mine for less than 1/5 of that [~200zł and 1$=3,5zł]).
As for usage :
Rampage has a PROPER MOSFET cooling solution (ie. heatpipes + screws).
The attachment Doom 3 XP 5,1GHz Rampage GPU OC.PNG is no longer available
My P5K64 WS had weak cooling on top MOSFETs (heatsink wasn't pushed down strong enough and that resulted in bad contact with mosfets).
I discover this when was pushing my Pentium XE 965 past 4,8GHz.
Push pins simpy aren't good enough with stock 0,5mm pads.
I had to used improvised "washers" to make spring compress more for result below :
The attachment Doom 3 XP 5,02GHz 198FPS.PNG is no longer available
However it only helped in short term tests (Cinebench R15 was too long and result droped because of throttling), in longer tests P5K64 WSs VRM can't handle that power hog even with active cooling on all heatsinks (results drop accordingly with time, same as GPU Boost 3.0 from latest NV cards).
Back to Rampage :
It's a awesome MB (no MOSFET overheating), and Socket doesn't have problems unless you go LN.
Reason for problems comes from big capacitor undreneath it :
It simply gets it's contacts screwed up with too much force on heatsink/LN pot (and under sub zero temps contacts crack easier).
If you can live without DDR3 buy Rampage Formula or EP45-UD3P/UD3R, and if not think about Maximus Extreme (should be cheaper than Rampage Extreme).
PS. DDR3 vs. DDR2 :
1) You don't really need DDR3 unless you want to go 450MHz+ on FSB and still have 8GB RAM.
Why ? Because 16GB DDR3 can be cheaper than 8GB of 1066MHz+ DDR2 variety 😀
(oh, both ASUS boards support 16GB of RAM, just make sure DIMMs are Dual Sided).
2) From speed perspective alone... DDR3 isn't worth it. IMC settings are more important than RAM itself. Also, high capacity DDR3 RAM can't go really fast on LGA 775 boards.
I managed to do 1600MHz with 16GB, however going over that prooved... troublesome.