I recently bought 1" of 19ILD blended talalay from SLAB. Took slightly under 2 weeks to get.
It is pretty nice, but the 1" of 100% natural from RMM seems a little nicer. The SLAB has a definite glue seem, but I put it on the side I don't sleep so not an issue for me. Don't think I would feel it anyway. 100% natual seems a little nicer (less synthetic - no surprise) than the blended, maybe in part because it is an end piece that is smooth on one side. The holes seem a little bigger and more definited on the 100% natural as well. I don't think any of this means much in terms of performance.
As expected, the 19 feels a bit softer than the 24, but more supportive than the piece of memory foam I replaced it with. Last couple of nights I used on top of Sealy coils, 2" of 32 100% natural talalay, 1" of 5lb. Sensus, 1" of 19 blended Talatech, 1" of 24 100% naturual talalay, covered with Natura washable wool mattress pad. I used without the wool topper to get more of a feel of latex. Might be slightly softer without the topper - not sure? Anyway, I am pretty happy with this configuration. A bit firmer and more supportive than when I had the 2" of MF, but maybe slighlty more pressure points. After a while, and the mattress warms up, it does seem to mold to the body reduce the pressure points. I think the 1" of Sensus helps in this a bit.
I did not have heat issues without the topper, but it was a cool night. I am putting the topper back on to see if I notice a difference.
As far as will 14 give enough support? I think a bit more than MF, but maybe not a lot. SLAB does allow returns, so if it is too soft you could exchange for a 19. You will probably losing shipping costs both ways and maybe some handling fee.