I run both in my set up and they work well. Unless space is an issue I don't see any reason to buy xs batts. Don't know how much power you plan to run, but a good HO alt is your best investment
All ready got the ho alt let me tell u I'm in love with the **** thing //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif ill be running a sundown saz 3500 I'm hoping xs has a group buy soon