I built my own using the LI talatech slabs you mentioned (at a much lower price I might add) and neither my wife nor I have any problem with smells. In fact, there never was any even when I unboxed and unwrapped the individual slabs from their shrink wrap. Here’s me and a friend filling the encasement with the 3 slabs. A detailed description of what I used is on page 3.
https://forum.mattressunderground.com/t/mattress-cover
I would think that the pure “natural” latex would off gas compared to the blend. You’re much better off going with the synthetic/natural blend latex aka ‘talatech’ for many reasons - durability, no smell, lower price. LI makes a very high quality, consistent, quality controlled product.
Good luck,
Mark