"2) Cast iron gonna get kinda fragile in long sizes. You're only gonna
drop it once!"

Since long jointers are not held and moved, but stand in a fixed
position in a cooper's shop, you'll be hard pressed to drop one. Most
are wooden,but cast iron example do exist. 

https://www.oldtoolmart.co.uk/onlineshop/prod_7237936-Coopers-jointing-plane-
Briggs.html


"Made by Briggs in Burton-on-Trent, a town made famous by it's
breweries. 

It is 5' 8" long and has a cutting width of 3". The iron is by Fearns of
Sheffield."  The stand is also cast iron. 

In my coopering files there's a photo of another, French as I recall. 
Wood cooper's jointers are often as long as 6 feet, sometimes longer
still.  Mine's a baby at 4 1/2 feet, a D.R. Barton, with a blade set at
25 degrees.  A joy to use. 

Mike in Woodland