Regarding #77 Yankee Jacks vs #78 American Jacks, I 
wrote the following in response to an early query-- and still hold to it 
for myself:
	
		
	
	
		
		
			... why is it that the 77s have all been so warmly received, when the 78 did not?  I own only our forum knife, but aside from a few subtle variations the two patterns appear very similar.
		
		
	 
Compared to a #15 Jack (a mostly-known quantifier, in whatever clothes), the #77 Jack is only yee bigger here and there, leading to a similarly-proportioned, mid-weight knife in a larger size.
Compared to a #77, the #78 is just a yee bigger here and there, but with a little more than one-step-up weight-- it's built tough and sturdy, with a snap to match. It's a hefty handful.
Comparing a #15 to a #78, which was the only "step up" at the time the #78s were released? The #78 is clearly a massive beastie.
Me, I love the #78s, especially in Tidioute clothes-- namely, a well-placed nail nick as per the above, so that I can leverage the blade open. They are snappers. However, given the expanse of cover material, I want(ed) a shield, which the Tidioute models do not have.
... When confronted with so many wonderful (and ongoing!) patterns from which to choose, one must make decisions. I would love to own a #78-- a true workhorse, and I love me some strong pull-- but the #77 comes together for me as a pattern in a way the #78 doesn't, right down to the pen-behind-main.
		
		
	
	
Or maybe it's just that mine 
glows? ;-)
~ P.