We were hit with the same rude surprise when we migrated.  Short version - keep DTS on 32-bit.  It might run, but you are on your own if you do - untried, unsupported, etc.

We kept our old 32-bit boxes as the DTS clients, then quickly made some of our packages dynamic so logging and connections happened corretly.  It caused a lot of scrambling and grumbling, but we are the poster child for dramatic performance improvements on 64-bit.  Pay the piper.

Email me if you want to discuss our experiences more.

Larry