the WS vs maxliffe or other fluids has been beat to death on here & other forums... fact is the maxlife & other "universal" fluids have been developed to meet or exceed any specs WS is rated for. need to remember WS was devolped for toyota back in ~2003 when they started to use the sealed trans. major lubricatioin companies like valvoline (ashland) & amsoil etc many years later developed a fluid that can meet or exceed many different companies fluid specs. i would trust a modern fluid designed by companies that specialize in one thing, lubrication fluids. & it is also a fact that synthetic fluids are much better than conventional fluids of any kind, its not just about cold temps, synthetics have better lubrication which means less friction, they handle heat far better & will last longer. maybe for 1 guy that lives on an island & doesnt drive much or ever abuse/tow with their vehicle WS is ok & im sure its ok for many other situations, but why would you pay more for a lower quality product?
its kind of like motor oil that was a SM API spec back in ~2000, since then oils have come a very long way & now SN & SN+ dexos oils are far superior to 20 year old SM oils & using the newer oils wont harm anything on older vehicles. why would anyone use 20 year old SM oil technology (if it was still sold) vs a newer better oil? same applies to WS vs a newer better full synthetic.
& no, WS is not lifetime fluid, the owners manual clearly says to change it at 60k if it was towed with or even just driven in very hilly areas like colorado etc, otherwise its 100k recommended intervals regardless of how the vehicle is driven. yes, you can go to 150k-200k+ miles & the trans will probably not blow up, just like you can go 10k miles on oil & the motor wont blow up, but it shortens its life & causes more wear than needed.
buy the fluid you want, they will both work ok, but just realize there are better fluids today than WS or even 15-20 years ago oils.