I found this pdf document comparing the Adaptec 5 series with the LSI 3Ware and I thought it was worth a look.
http://www.adaptec.com/NR/rdonlyres/AD611737-2A60-4AEF-9E08-1DC6B7D81242/0/3Ware_Competitive_DB.pdf
http://www.adaptec.com/NR/rdonlyres/AD611737-2A60-4AEF-9E08-1DC6B7D81242/0/3Ware_Competitive_DB.pdf