As BurningPlayd0h says the above table is for blackbody radiators. The actual figures for leds are very different because they put most of their energy into visible spectrum, this means the difference between 4000K and 6500K in leds is a lot smaller.
Asking me what S2+ emitter would I choose? My preferences are quite a bit different, JagerLion. I do not really care much about efficiency as it is a magnitude weighed by the luminosity function, and I dislike the fact that the large ignorance in these subjects has delayed a lot the development of led blackbody radiator accurate light sources. To me, along with photographers and film-makers, light source quality is absolutely paramount.
What I most care about is about comfort and rendering accuracy. Given that I also in some way support the findings of Arie Andries Kruithof, as a rule I prefer lower CCT with lower illuminance levels. This the reason my bedroom light is 3000K high CRI led, and I also use a cozy 2700K 25W tungsten bulb powered lamp (I have a bag full :-) of them).
If you really need to extract the most of your energy, I'd try to find the most efficient buck driver. The LD-29 is really good, unfortunately it is Ø20mm so not suitable for the S2+. The problem basically is that you are asking for something most don't fully care about, which is maximum wall plug efficiency or maximum electrical to optical power efficiency. And in this respect an efficient driver is very important.
This AA / li-ion driver looks like a nicely designed boost / buck driver, uses an R050 sense resistor which at 2A drops 0.1V, this is my guess about its maximum driving current as it is meant to be fed with Ni-MHs and at that level of power to the led the input current from a Ni-MH is already at 6-7A. However this is all guesswork and the plain lack of any kind of information is disturbing.
Then there's this 2.5A buck driver “theoretically” meant for red leds. But it is a buck driver, and so it will work equally well with any standard emitter, regulating for as long as the input voltage is high enough. The wrong thing about it as I see, is the piss poor sense resistor setup with a combined 0.1Ω resistance, this means a whopping 0.25V of drop when 2.5A go through the sense resistor stack, i.e. a lot of loss which shouldn't be there when sense voltage could just be 0.05V, for example. In other words, its efficiency could be better and also its regulation time and window are lower just because of its unnecessarily high sense voltage.
If you still insist in asking me about what emitter would I choose… wellp, remember I am not you. I myself would likely lean to something between 2700K and 4000K. Maybe in your particular case I'd probably try a 5000K CRI90 LH351D (F2R2S2 so 5000K leaning low), but I am saying this just because I am trying to put myself in your shoes. 5700K CRI90 LH351D is also available (it is V2Q1S2 and its CCT is 5700K leaning high, the ad title has a typo -it's not V2Q2S1-), but that's already very far away off my preferences.