I have a GoPro Hero3+ Black and my vids are shot at 1080/50 PAL.
The quality is truly amazing and I shoot at 50 frames thinking that it is better for slo-mo than 25 fps.
I normally go through the lengthy process of of using GoPro Studio (latest version) to trim and convert all files to AVI and then import into my PD 13 Ult.
My observations are as follows:
1) GoPro Studio AVI show a loss in video quality when compared to the MP4 video.
2) If I import both the AVI and MP4 clips onto my timeline the rendered output quality is better on the MP4.
3) The GoPro Edit effects on the generated AVI files (SloMo etc) is not as good when imported onto my timeline as the same effects applied on the original MP4 file using PD 13.
4) PD 13 seems to handle GoPro Mp4 just fine so I no longer use GoPro Studio or generate those huge AVI files.

I may be wrong so would appreciate feedback from other GoPro users -Thanks.

Question - What happens to a the 1080/50fps MP4 clip when I import it onto my PD13 timeline and my Project setting are 25fps. I get a warning of a frame-rate conflict, click OK and it is added to my timeline.
Is converted to the project frame rate (25fps) by PD or does it remain as 50fps - which should give me better SloMo results frpm Power Director??? Power Director 13&14 Ultimate, Photo Director 6, Audio Dir, Pwr2Go 10
Win 10 64, Intel MB DH87MC, Intel i5-4670 CPU @ 3.40GHz, 16Gb DDR3 1600, 128Gb SSD, 2x1Tb WDBlue 7200rpmSATA6, Intel 4600 GPU, Gigabyte G1 GTX960 4GB, LG BluRay Writer