i have a 550, and while I don't use it for the sounds anymore, they are surprisingly decent for a newbie board like that. That said tho, the effects section is super limited, as is the general sequencing/mixing capabilities of it, so you'll find that extremely extremely limiting.
Unless you absolutely must have a hardware board for your sounds for some reason, you'll probably find a software sample setup to be 13209870x more powerful and flexible, unless you spend thousands for a workstation keyboard like teh Motif.