There aren't really as many cons for 64-bit Linux as there are for 64-bit Windows. Most open source applications support 64-bit, but the closed source ones might give you problems if they don't offer a 64-bit version. Flash, for example, is only 32-bit, so you have to either run 32-bit Firefox or use nspluginwrapper. Alternatively, there's an open source version of Flash called Gnash but it still has some bugs. Ubuntu can set up Flash automatically for you on a 64-bit machine, but I don't know about SUSE.