Well do you think you might possibly get more snakes in the future? If the answer is an absolute no, then no you dont need a Herpstat 4 or 6. If it is possibly, then i would say just spend the cash now and be done with it. Wish I had done it that way to begin with. I sold off 2 Herpstat 1 and 2 Herpstat 2. The cash i lost being it is used and an electronic item, i could have probably have bought half a 3rd Herpstat 6 lol. But when i bought all my Herpstats 1 and 2, they didnt have the 6 out yet.