I like the SFX for many subjects where Konica would have been a bit over the top. I used and loved Konica, as well, but for different subjects. The SFX gives me beautiful textures on steel structures, both painted or rusted. It's also great for some rock formations and masonry. Nice and contrasty, but with lots of detail in the 120 format.
I'm thrilled SFX is back. I miss Konica. The Efke 820 is great, but again different from any of the others. I haven't found its perfect niche for me yet, but I'll certainly keep trying.
Apart from SFX, which of the IR films has the least sensitivity to IR?
The current Rollei film (not the new one they're currently testing) is also an "enhanced red sensitive" aerial film by Agfa-Gaevert. Quite similar to SFX, but I still prefer the SFX, especially it's cost.