The Extreme Edition is massively overpriced (IMHO) and also has cache ECC turned off (not a good state of affairs - but as it was targetted at "Gamesters" in the PC market Intel probably felt nothing too critical would be effected should things go a bit "tragic").
It would probably be more prudent to wait for an appropriately fast PC CPU (rather than a "forced" arrangement like the Extreme) to arrive.
Extreme would still be slower (but closer to) the Iyonix in performance terms - - - but probably just as expensive
[Dabs price the 3.2GHz Extreme at a stunning 648.99 gbp and that's just for the processor !!!!]