Minor correction to this, that I figured out by reading the manual etc: A Time Warp video comes out as 30FPS. So you can figure out the frames per second by taking the time warp factor and dividing it into 30.
For example, 2X time warp is 30/2 = 15 frames per second taken.
5X time warp is 30/5 = 6 frames per second taken.
The 5X time warp seems to work well when driving, even at freeway speeds - and the big upside is the file is 1/5 the size, so can fit a LOT of hours on a typical SD card.
There is likely even more space savings because Time Warp doesn’t record sound - and that part of the file is quite large as well. (Though if video recording you can disable sound via GoPro Tools, which presumably has the same savings.)
(I am having a problem with uploading these files using mapillary_tools, outlined here, but that is more of a minor detail.)
I haven’t compared this with just shooting straight video, but as a guess the quality will be the same or very close.