The Allendale are the E6200, E6300 and E6400. All with 2MB of L2 Cache.
http://en.wikipedia.org/wiki/List_of_Intel_Core_2_microprocessors
The Conroe's E6600, E6700 and X6800 have 4MB of L2 cache.
Reading the XS thread, it looks like the DS3 is good for high FSB with lower multipliers 6/7/8, like the Allendales. The retail E6600 has a locked multi of 9 and the DS3 seems to be hitting an FSB wall <400MHz with higher multi's. The E6600's you've seen on the DS3 have been ES (Engineering Samples) versions with unlocked multi's