Today, I spent more than one hour trying the 43 and 43 1/2 size (La Sportiva recommended me 43), up, down a steep slope, walking around, again and again. I wear normally La Sportiva 43 (Nepal Extreme, Trango S, and Cirque Pro) or ski shoes 275mm (Salomon, Dynafit).
Dear Anonymous, Indeed, the shell outer size might be the same between 43 and 43 1/2 (thanks to your review, I checked and you might be right), but the inner life is slightly larger in the 43 1/2 than the 43:
- the inner sole bed is slightly longer in the 43 1/2 than the 43 (remember: half French size is only 3.3mm, 0.13in):
- down the slope, I touched the tip of the inner boot with the 43, and slightly felt the tip of the inner boot with the 43 1/2;
- I felt a tad too much "compressed" in the 43, not the case in the 43 1/2;
- I can add up a second thinner pair of socks in the 43 1/2.
I went for the 43 1/2, not a big difference (3.3mm in length) but felt better and enough room if my feet swell (one side effect of altitude besides AMS).
Take the time with the Spantik as they are quite snug fit (I have rather a narrow foot) and the difference between two half sizes makes the difference, indeed (44 was definitvely too large), do not hesitate to walk down a slope (toe contact?) and go up (heel lift?) to feel comfortable in the shoe.
They are way better than plastic double boots (my Scarpa Vega aka Inverno inner boot failed and totally gave out, I was just floating in the shoe), much more comfortable ( I started a few years ago with the Vasque ICE 9000, great shoes but too roomy for my heel and front pointing became a torture), and precise (yes one can climb with those newest generation double boots).
So now I have the field test to complete, but with the experience of the the ICE 9000, I have no doubts. La Sportiva simply rocks and celebrate 80 years of success.