played with these @ ces. 111 bclk is actually really really good. we were also finding that the multithreaded performance isnt quite what it should be in few synthetic benchmarks we tested so the 2500k would be our weapon of choice for the moment unless some updates become available.
this is a great chip to bench the 3dmark series as well as heaven.
the whole 4.8ghz 4.9ghz wall is unfounded. intel released bios microcode update for d2 chips (all retails are d2 afik) that ulocks pll overvolting. also, talking with 5 members of the sandybridge design team, they stated that all retail chips should be able to do 5.2ghz. when questioned again about this, they were very atimate in stating that EVERY chip can do 5.2ghz.
just my 2 cents.