The frame is indeed the only new design on the P40.

As said, when Pacific Cycles developed the frame for the 40th anniversary of the company, thy hoped that it could become in a second stage part of their mainstream product line.

But if I understood well, Riese & Müller is the owner of the IP of the Birdy including the Birdy name and because they were not involved at all in the development of this new frame, they didn't allow Pacific Cycles to commercialize it as a Birdy product. Its not only a question f brand name and IP, Rise & Müller is a german company, they refuse to put on the market anything that isn't fully tested by themselves according to the TÜV requirements.

So the P40 frame remain a frame for only an anniversary bike with a limited number of pieces produced with as consequence that Pacific Cycles had to amortize the development costs on a small number of pieces which mean a higher price or/and cheaper components.
I also wonder if Pacific Cycles was not originaly intended to lso develop a new fork and rear suspension arm but stoped that and used the parts of the Birdy 3 to limit the development costs ?

For the development costs to be amortized on a small number of pieces, its also the case of the titanium Birdy that has a fully redesigned titanium frame, main frame+fork+rear swing arm what was very expensive and to be amortized on only 250 pieces with as consequences a very high price of 6500 USD and some low end components like the wheels.