I love this toy.
It feels like it is bigger than any car based TF I have gotten in a while. The flash of the camera doesn't do it justice in some ways. In normal room light you can hardly see the joins and panels. I took it to work in vehicle mode and showed a few guys and they didn't even realise it was a transformer.
I had the same trouble with the abdomen so I will use your advice when I transform it yet. The only downside to me was the blocky part under the front bumper and engine where the batteries go.