Moving from ReadyNAS NV to Pro 6 - Best plan?

ok... so I backed up the TimeMachine from the NV+ to the Pro first with NFS (800GB takes 20 hours) and then incremental with rsync to a share called "Tmbkup". Turned on TimeMachine on the Pro, then turned it off. Then I smb'ed to the pro:admin/c and moved the sparsebundle to c/.timemachine. Then turned timemachine back on. I set my Mac's timemachine to point to the Pro and... it can enter timemachine ok. (and yes, there's another bundle there for another Mac, but I haven't tried that one yet)

However, when I tried to do a timemachine backup, it kept giving errors and trying to expand sparsebundle and deleting lots of old backups, etc. never actually backing up. Looking at console I see lots of messages e.g. (until I cancelled the backup):

1/4/12 8:34:01 PM com.apple.backupd[7853] Starting standard backup 1/4/12 8:34:01 PM com.apple.backupd[7853] Attempting to mount network destination using URL: afp://readynas@mynas.local/ReadyNAS 1/4/12 8:34:03 PM com.apple.backupd[7853] Mounted network destination using URL: afp://readynas@mynas.local/ReadyNAS 1/4/12 8:34:03 PM com.apple.backupd[7853] Error writing Time Machine Information file: /Volumes/ReadyNAS/my.sparsebundle/com.apple.TimeMachine.MachineID.plist 1/4/12 8:34:03 PM kernel ASP_TCP CheckReqQueueSize: increasing req queue from 32 to 128 entries. so 0x1d2986a0 1/4/12 8:34:03 PM kernel AFP_VFS afpfs_mount: /Volumes/ReadyNAS, pid 7854 1/4/12 8:34:03 PM com.apple.backupd[7853] Resizing backup disk image from 800.0 GB to 2125.7 GB 1/4/12 8:34:13 PM com.apple.backupd[7853] backupd: resize request 4457992024 is above maximum size 4294967216 allowed. 1/4/12 8:34:13 PM com.apple.backupd[7853] Could not resize backup disk image (DIHLResizeImage returned 22) 1/4/12 8:34:14 PM com.apple.backupd[7853] QUICKCHECK ONLY; FILESYSTEM CLEAN 1/4/12 8:34:15 PM fseventsd[38] could not open <</Volumes/Time Machine Backups/.fseventsd/fseventsd-uuid>> (No such file or directory) 1/4/12 8:34:15 PM fseventsd[38] failed to store the uuid in /Volumes/Time Machine Backups/.fseventsd/fseventsd-uuid. unlinking it. 1/4/12 8:34:15 PM mds[32] (Normal) DiskStore: Creating index for /Volumes/Time Machine Backups/Backups.backupdb 1/4/12 8:34:16 PM com.apple.backupd[7853] Disk image /Volumes/ReadyNAS/my.sparsebundle mounted at: /Volumes/Time Machine Backups 1/4/12 8:34:16 PM com.apple.backupd[7853] Backing up to: /Volumes/Time Machine Backups/Backups.backupdb 1/4/12 8:34:16 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:16 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:16 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:19 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:19 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:19 PM com.apple.backupd[7853] Exception writing exclusions cache. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:19 PM com.apple.backupd[7853] Unable to create exclusions cache data. 1/4/12 8:34:19 PM com.apple.backupd[7853] Failed to write exclusions cache. Continuing anyway. 1/4/12 8:34:19 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:19 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:19 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:30 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:30 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:30 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:30 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:30 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:30 PM com.apple.backupd[7853] Error writing to backup log. NSFileHandleOperationException:*** -[NSConcreteFileHandle writeData:]: No space left on device 1/4/12 8:34:30 PM com.apple.backupd[7853] Backup canceled. 1/4/12 8:34:30 PM fseventsd[38] disk logger: gzclose() failed (-1/28) removing all old log files in /Volumes/Time Machine Backups/.fseventsd 1/4/12 8:34:30 PM fseventsd[38] failed to store the uuid in /Volumes/Time Machine Backups/.fseventsd/fseventsd-uuid. unlinking it. 1/4/12 8:34:31 PM com.apple.backupd[7853] Ejected Time Machine disk image.

Opening the sparsebundle with diskutil shows ~170GB available.

Huh? What do I have to do to get the timemachine bundles copied over from the old NV+s to the new Pro ... and working?