Yeah it's directed towards you.

Just buy the Tammy, don't go lookin' for reasons to add to it until you build it. You can get and install metal tracks anytime. Just drop the $600 and get the Tiger.

The IV is neat, a great runner but I'm not wild about the turret config, it's the only Tammy turret that you can't pull off. It's small and yes it fights as a medium.

Personally, if you're going to spend the $700-800 on a newer kit (keeping in mind the Tiger I is still their best engineered kit and a steal at current prices), I'd go either JP over the IV. Yeah you don't have a turret, but you can just learn how to drive...