Hi!
I agree with you about Hasegawa kits specially the 1/48 Tomcats, they are complex, a lot of pieces and have tricky sections, some times specially the first time you build one you can be a little frustrated, you will need patience and I think a little of skill too. One thing I not agree with you is about the size of the YF-19, looking at mine, the fuselage is almost the same size of the Tomcats, and you need to add the "legs" and the exhausts, son I think is the same size of the Tomcat or even bigger About the complexity, agree with you is on pair with the Hornet.