too big and you are only adding chopping power, like say 22-Rimfire's example of the BK7 vrs the BK9.... while true if you are running a 1 or even a 2 knife rig, like coupled with a BK16....the 9 just makes more sense.....
however, I run a 3 sharp rig, and my 3rd woods sharp is a Silky Saw so I just don't need to chop much of anything, I do use a larger blade for baton work to split larger diameter stuff and save the 16 for fine carving tasks.... in a rig like I run, the 7 would be every bit the equal of the 9.....though I always carry the 9 anyway just because I have both and occasionally I just WANT to chop at something....
7, 9....your call, the 9 WILL chop better, but the 7 ain't bad....
ETA: just incase it wasn't obvious, my vote is for the BK over the Sog.....I've seen enough of those rubber overlay handles go bad during use to ever own one on what I would consider a working knife....I just don't trust em to hold up without eventually splitting out...and I won't even start on the difference between exposed full tang and what's typically inside the rubber covering....