Birds move very quickly, so 10 fps can help get the right micro-moment for a best image. This does not mean shooting long bursts, but getting more frames per short burst.
I have never used an 80D, so cannot say whether a 7D II is worth the trouble to upgrade. I started serious shooting with a 40D, then added a 7D, then soon, a second 7D, so I would have a pair of cameras to use at work, with identical controls and identical WB settings, with an EF 100/2.8L Macro IS on one body, and a zoom lens on the other. (Evidentiary/forensic/crime scene photography.) I upgraded to a pair of 7D II cameras soon after introduction. The differing buttons on the cameras’ top right “shoulder” kept me from liking the 60D/70D/80D/6D cameras.
The 1D-/1Ds-series cameras are wonderful. I have no experience with the 1D IV, but very nearly bought one, pre-owned, and do have a 1Ds Mark III. I love these solid, pro-level cameras (These have buttons that differ from the 7D-series, but the 1D/1Ds, from the Mark III onward, have the all-important ISO button in the equivalent position as on the 7D-series.)
Google Grant Atkinson; he is a photographer in Africa who has posted a good comparison of the 7D II and 1D IV.
The weather-sealing of the 7D II and the 1D-series is reassuring, if caught in a sudden downpour. (While on duty, I had to keep shooting, sometimes, in the rain.)
This is just my $0.02; not an attempt to make a specific recommendation.
@RexGig wrote:Birds move very quickly, so 10 fps can help get the right micro-moment for a best image. This does not mean shooting long bursts, but getting more frames per short burst.
I have never used an 80D, so cannot say whether a 7D II is worth the trouble to upgrade. I started serious shooting with a 40D, then added a 7D, then soon, a second 7D, so I would have a pair of cameras to use at work, with identical controls and identical WB settings, with an EF 100/2.8L Macro IS on one body, and a zoom lens on the other. (Evidentiary/forensic/crime scene photography.) I upgraded to a pair of 7D II cameras soon after introduction. The differing buttons on the cameras’ top right “shoulder” kept me from liking the 60D/70D/80D/6D cameras.
The 1D-/1Ds-series cameras are wonderful. I have no experience with the 1D IV, but very nearly bought one, pre-owned, and do have a 1Ds Mark III. I love these solid, pro-level cameras (These have buttons that differ from the 7D-series, but the 1D/1Ds, from the Mark III onward, have the all-important ISO button in the equivalent position as on the 7D-series.)
Google Grant Atkinson; he is a photographer in Africa who has posted a good comparison of the 7D II and 1D IV.
The weather-sealing of the 7D II and the 1D-series is reassuring, if caught in a sudden downpour. (While on duty, I had to keep shooting, sometimes, in the rain.)
You might like this quote (about one of the 1D-series cameras) that I attribute to Ernie Biggs. I'm not sure he originated it, but I'm pretty sure he's the one who told it to us: "It's so tough that you could bash somebody's head in with it and still use it to take the crime scene pictures."
I did not originally say this, ""It's so tough that you could bash somebody's head in beat somebody to death with it and still use it to take the crime scene pictures.""
I have heard that for 20 years give or take a few. I wish I had said it, though.
A word about all the bickering about this one is best at xxx and the other one is best at xxx, is mostly baloney. It is good fodder for the laboratory but not outdoors in the real world. If you intend to take photos of a lab I guess you better heed it but otherwise pick the one you like.
Let me say if you can't get a shot of a BIF with a 7 or 8 fps camera a 10 fps camera won't get it either. 
