You absolutely need a breaker in the panel, and could choose to make that breaker your single GFCI for the whole system... for me, it was cheaper to buy a spa panel with 50A GFCI breaker, a regular 50A non-GFCI breaker for my panel, and 15 feet of 6/4 wire, than to buy a 30A GFCI breaker for the panel by itself and 15 feet of 10/4 wire. I still don't understand why the pricing works like that, but it ended up giving me future expansion flexibility for my 5500W system.
Primary: eSCB IPA 11.13
Bottle Conditioning: eSCB Holiday Ale 8.13, eSCB Gingerbread Stout 9.13
Kegged: eSCB IPA 5.13, eSCB Holiday Ale 8.13, eSCB Gingerbread Stout 9.13
Commercial Tap: Air
In Bottles: Flying Dog "The Fear", DFH 90 min, SN Torpedo
Gallons in 2013: 116