I did not notice much difference with different pitch props on top and bottom except the esc/motor temps. With the Hexacrafter X8, good stiff carbon props seem to be the best. Either Foxtech or T-motor props. This set up seems to provide the most consistent performance. The 3 blades on an X8 with the coax wind was seriously horrible. BUT they work pretty darn awesome on a flat machine. The 3 blades smoothed out my hex really well. I just think the fact that the folding property has to fight the wind coming down on the lower props makes for a problem.... But hey, this is just my opinion.
As far as the Hexacrafter frame, I can't recommend them enough. OH you want to mount that new thing to it? Andrew probably thought of that and has an attachment point, or a device to allow it... 100% top quality stuff.