It really, really comes down to personal preference and how you use a knife.
A person who doesn't intend to chop anything will find the FK2 all that they'd ever need in a camp knife. Same goes for someone who uses a knife solely for cutting, and brings an axe/hatchet for chopping.
If you like to be able to use the same knife for cutting and whittling, and might want to do a little chopping and batoning (but don't carry an axe/hatchet), the HDFK has the advantage due to size.
Personally, over years of camping, my personal preference has gravitated towards large camp knives (9" - 10" blade length) . My current LCK of choice is the CPK Medium Chopper.
The reason for that is due to my personal preferences. I rarely ever carry an axe/hatchet in the woods. My typical loadout will include the MC, a pocket folder and a folding saw.
Having gotten used to large knives, I can use the MC for just about everything I'd use an HDFK for, but have even more chopping power, and the ability to baton pieces of wood as large as I'd ever use (I generally don't bother with anything thicker than 8").
If I really need a small knife for fine work, I use the folder. For my preferences, I've found a longer bladed large knife to be more versatile than an axe/hatchet, because I can use it on brush.
The advantage of an axe/hatchet in chopping thicker wood is not a concern because I simply don't do that when camping.
If I specifically need/want to chop something 12" or thicker, I'd bring an axe or chainsaw.