why averaging only 4MB/s and how to spare bad blocks?

[sjs]

hi, thanks,
i dont know what you mean with this line

"OSX will actually compact FileVaults automatically, so it should work automatically post-bloat."

are you saying that after a destination sparse image gets heavily fragmented and bloated, a simple deletion of all files automatically triggers os x to compact any given sparseimage? what is the trigger? a certain threshold of deletions or too much fragmentation? i don't think i am understanding what you are saying... i thought the trigger was a Log Out User, and it only applied to File Vaults, not sparse images destinations that SD creates that aren't subjected to any Log Out process...

can you talk about what an Erase than Copy does? Does it format first or just delete files first?