UTDC 2.0 had some bugs.  Not only did it throw false positives but it crashed 64-bit machines.  Which is the reason why {dFb} still uses 1.8.  I customized the UTDC 1.8 ini to catch some cheats that 1.8 normally doesn't catch though.  Can't comment on 2.1 since I havn't looked into UT99 in a long time but it may be better than what we had to put up with using 2.0.

This is our 1.8 UTDC ini:

http://emac.dfbgaming.com/UTDC_ini.txt