There first few hours people were trying to figure out if there was an "xploit" they could take advantage of. The hash is more stable now verus the first few hours.

Check out the awesome chart on coinium to see: http://digi.coinium.org/

Before DigiShield took effect the same hash swings occurred, accept now we are not "stuck" for 2-3 hours and the difficulty adjusts within a couple blocks to hash swings both up and down.

We tested over 50 different configurations over the course of 5 days including the Kimoto Gravity Well and other approaches. The DigiShield configuration out performed all other configurations and is essentially a sum of what we learned and applied from other setups.