Sigmarion 3 works with 64GB microSDXC!
The way I made it work is that I bought a SDXC to Compact Flash adapter called ADR-SDCF2 by SANWA Supply. Since you can't format microSDXC to FAT32 by default on Windows OS, I used Ridgecrop Consultants' fat32format GUI version. (Click on the screenshot to download their site).
I used a microSDXC to SDXC adapter then inserted that to ADR-SDCF2. 64GB microSDXC works like a charm on my Sigmarion 3!
See you till next time!