While I did replace my converter with a lithium compatible version, in retrospect, I didn't need to. My 320 watts of solar through a lithium compatible solar controller provides most of the battery recharging. The WFCO probably won't go into bulk so it won't bring the lithium batteries to full, but the solar controller will usually provide the final 20%. Since you primarily dry camp, the converter isn't as necessary as it would be for those without solar that camp with utilities.
As pianotuna said, try it first. I'd only make the change if I had to depend on a generator to recharge the batteries. A lithium compatible converter will shorten charging time.
