My opinions on some of the things mentioned. To compare the AZ Mk IX to the Hasegawa kit is a disservice. The AZ kit is less than a MM shorter than the Sword Mk IX and nowhere near as anorexic as the Hasegawa kit.
The plastic is the same in the Sword Mk IXe and highback Mk XVI kits, so yes it could be built either way.
Comparing the Hasegawa and Sword Ki-84's side by side they are practically identical. The Sword kit is not "chunkier" but is scribed. Quality kit, buy it with confidence.
Don't know if anyone mention the FM Me-109's or Hasegawa Fw-190's, both are very nice If a little light on cockpit detail.