Worth remembering that the the CT40 is a CT and not the conventional round that is often discussed when talking 90mm and 105mm.
CT40 actually means a 65mm case competing in the 50mm SuperShot category and not 40mm.
The second, before we move onto calibre, is what platforms in what numbers and CONOPS?
The third question, before calibre, is what is available? CT40mm has entered production. 120mm turreted mortars with direct fire likewise. There are few 90mm and 105mm with the turret elevation and natures out there.
*I know, I know
2) Direct fire support in the 120mm category.
I'll tackle the latter first.
I'll leave you in peace for a bit.
/FIN