The only difference I can see between the two cameras is that the XF405 has HD120fps, 4k60fps, while the XA55 tops out at 4k30FPS (and I don't think it has HD120?) Both cameras have 3g-SDI ports that I can hook to my Shogun. I believe the XF405 records internal 4:0:2 but will send 4:2:2 over SDI? Has anyone read what comes out of the SDI port on the XA55? I couldn't find any info.

Trying to decide which of these to purchase. I am shooting mainly live events. 4k30 would probably be enough for the concerts, but not so much for sports, which is why I'm edging towards the 405.

Has anyone clocked how fast the battery drains if you're using the phone app to control the settings on the XF405?

Sorry for the scatterbrained post, I'm falling asleep at my keyboard here.

The LCD screens are different. XF405 is 3.5" 1,560,000 Dots. XA55 is 3" 460,000 Dots.
I recently purchased the Canon Vixia HF G50 and already had the XA20 and the G40. The G50 had the 3" 460,000 dots LCD and the XA20 and G40 have the 3.5" LCD. I really did not like the 3" LCD. I had a hard time telling if it was in focus compared to the 3.5" LCD. It's definitely worth the extra money for the better LCD screen and much more of a joy to use. Although the G50 did have magnification during recording and that did help some to check focus, I'd rather have the better LCD. I returned the Vixia HF G50. I really want to get into the 4K format mainly for the pan and zoom in editing and to mix with my other two cams. Not sure if I can justify the cost of xf405 or one with the better LCD screen. So the extra $500 for the XF405 is worth it because you will probably enjoy using it better than XA55, plus having the 60P option.

You also lose 30 X telephoto in HD.
The X 55 only has one DIGIC 6 processor and the XF405/400 has two