The biggest pain point (IMHO) with the X3 is the length of processing time/CPU power required to stitch the video before it is useful to upload (https://help.mapillary.com/hc/en-us/articles/11951588568604-Insta360-X3)
I haven’t seen whether the X4 addresses this in any way (my suspicion is that it does not unfortunately, which leads to the continued recommendation of the GoPro Max and PANOX V2 for consumer 360 capture for Mapillary)