Deletes are supported since
SQOOP-3149, but we're only deleting the last version of a column when the corresponding cell was set to NULL in the source table.
This can lead to unexpected and misleading results if the row has been transferred multiple times, which can easily happen if it's being modified on the source side.
SQOOP-3149 is using a new Put command for every column instead of a single Put per row as before. This could probably lead to a performance drop for wide tables (for which HBase is otherwise usually recommended).