I think you're going to see that bowing in almost any wide-angle video camera.
If you check this site, use the pull down under the Photo section and go back a year in the options, I've got a video called "Messing with the squids" where I use a front a rear VIO camera setup. Use the DOWNLOAD link on the VIO website and re-open it so it will appear larger on your screen. In the last few minutes, after the turn when the guy catches up to me, you can see the power line poles and see the bend near the tops near the corner of the frame. I don't think the VIO heads are much different than any other lens with regards to distortion.
There may be some software rendering programs to help correct the effect, might be called 'barrel distortion' or something like that.
The biggest issue I've had is the audio. Wind cause all sorts of issues. The newer GoPro HD seems to have that in better control than the VIO audio where the microphone is in the middle of the lead to the recorder.