Hmmmm, one thing catches my eye, it looks like this Brummbär is sitting neatly horizontal.

That's not right, Brummbärs were prone to a nose down attitude due to the heavier frontloading.

I am wondering if the sag in the Trumpeter kit is easily correctable.

On the assertion from a manufacturer that the leaf springs were indeed straight and would have been replaced when they were bent. This is an ideal situation. Bear in mind that the Brummbar were built on existing Pz IV chassis with no measures made to strengthen the suspension. Bent leaf springs (which they do not dispute) should ideally be replaced but how do we know if this was carried out religiously? Freshly produced Brummbars would have had straight leaf springs but these springs would have started to bend as soon as it was driven and employed in combat.

The bent leaf springs by Tristar do look a bit overdone but I have seen it with my own eyes and it does need to be bend that much to re-create the nose heavy look. You can easily replicate this by cutting the leaf spring on either a DML/Tristar/Tamiya Pz IV and positioning it with a nose down look. Then use some plastic strips to rebuild the leaf springs and you will notice that it does need to bend by that much.