I would study the chart of any k-boom, but wallboard cranes are just different animals.
Doesnt mean I ain't curious about them, but missing 1 knuckle is a big deficiency.
I know this is not your question. And I'm not going to steer this thread because I know your general knowledge of cranes is better than mine.
All I'm saying don't under estimate the value of 1 more knuckle up close to get under overhead obstacles (wires) or even to get over them.
The angles are also super, super important up high to position the boom to get the grapple into a canopy.
Sometimes part of your boom is mere inches from contacting a limb when going in for a pick. It is going to deflect some with the weight of the pic so you better position it to avoid contact. One more knuckle down low helps.
The wallboard crane w/ grapplesaw can make a nice combo... but like @TreeGuru4u said the extra articulation a foldable knuckleboom offers can be a huge advantage in many situations. If you would like to talk to an operator that used a Fassi F390SE.24 wallboard crane w/ grapplesaw for a year and just made a switch to a 65tm knuckleboom let me know... (Spoiler: he loves the knuckleboom)