I have switched to using cogs in the normal assembly. I think it was the perceived difficulty of cutting the half dovetails in the end bents that first drove me in that direction. I get turned inside out very easily and the cog, in my eyes, is an easier joint for me to figure, I also like how they are cut, no finicky corners to deal with.

Typically principal rafters and common purlins are used but I have seen common rafters and principal rafters used, I see this could apply additional forces on the dovetail and the cog. Which joint would work best to resist these forces?

Raising is also a deal. In a large building you need a larger crew to stand the long walls up and the difficulty of assembling the truss or a large gin pole set up to get it up in place. Of course with todays technology it is no problem. I have read this is part of the reason they switch to bent raisings it makes for a more friendly raising. And a segway to other tie configurations but let's not go there yet.

Tim