I live in the Pacific NW and propagation on all bands has been dismal for the last several years. I like working DX on any band and mode so FT8 has been a new challenge for me.
Recently I switched over to FT4 to see what is out there to work. I found that the activity level is considerably lower on the two primary bands I operate, 40 and 20 meters. My big discovery is that I have made many contacts on FT4 that most likely would no be possible with FT8. My observation is that there are very brief openings ranging from 30 seconds to 3 minutes where DX to Europe and other distant locations occur. Contacts using FT8 with these brief openings are usually not possible but FT4 works quite well.
I have chased a lot of DX on 160 m using CW and am used to waiting 20 minutes for a 30 second QSB peak to occur to work a DX station. These peaks are very similar to those I have seen on 40 and 20 m and FT4 seems to be the mode that can take advantage of them. I'd expect the same to be true on 6M where sporadic E and meteor bursts provide paths of short duration's.
I would like to see more DX stations to try FT4 on 40 and 20 m to see if FT4 maybe the more desirable mode for DX on some HF bands and conditions. One of the advantages of WSJT is that one can watch the waterfall to see the DX station before a decode happens so timing an attempt for a contact can be optimized.
Hope to work you soon on FT4!
Greg - W7MY