Just noticed, your PC-M4 is like three of the ones I got in my last shipment, all my others from even a few years ago were like the ones on the left. The one on the right may be what they are making now. It is an exceptionally strong slingshot and a bit thicker frame than the original even. It has more of an ergo shape than the original also, making it a bit wider in the pocket.
For the $ spent, you got your self a great, great frame. I'm waiting on the rubber tubing for the forks and then I will do one up to see how it comes out. I'm sure it will be great.
wll