Common mistakes when upgrading to 9i

Hi,

We are finally on a path to upgrade from 8i (8.1.7.4) to 9i (9.2.0.1).  I wanted to learn from your experiences on things that can go wrong. I am going to list a few things I've read up on, and if you're kind enough, you'll let me know if I missed anything important

• sga_max_size should be examied
• pga_aggregate_target default is 25MB, if set DB ignores sort_area_size hash_area_size bitmap_merge_area_size

How do above two affect MTS (Shared Server)         

• workarea_size_policy defaults to auto if pga_aggregate_target is set
• db_cache_size replaces db_block_buffers and is in bytes
• statistics_level defaults to typical
• automatic undo management should be researched (but not req'd)
• db_block_checksum is true by default in 9.2 (?)