I followed the Mac 101 instructions to copy my existing Time Machine backup DB to a new, bigger, disk. It seems to work with TM fine; I can see and restore the historical versions of files.
There is a pop-up question which happened about 30-40 minutes into the copy, (after "counting files" changed to 1,259,586 files 488GB). It had three options, I chose the farthest to the right. Don't remember what it said - sorry. Once I clicked that, the copy dialog read "copyed 0 bytes of 488GBB" and stayed that way for 8 hours. I opened a finder file info on the destination and could see that files were actually being copied.
After the copy ended, the copy did not appear to be the same as the original when viewed in BackupLoupe or Finder, but after selecting the new copy in TimeMachine and turning TM on, TimeMachine crunched for about 30-40 minutes, and Spotlight indexed the new TM disk for another hour (mds ran all four cores heavily), resulting in some sort of clean up so that all backups had the same number of files and bytes in them.
iMac Core i5 27, Mac OS X (10.6.8), Ext Blu-ray writer