They are different. 24mm and 30mm.

Jim's typical style of answering is less than informative. In fact, the difference he's asserting isn't even correct here. Simply because a frame is PF30, doesn't mean the crank needs a 30mm spindle.

You may need a different bottom bracket, but YES, the shimano crank will work in a PF30 frame.

Here's what a typical Shimano press fit BB looks like.

A PF30 frame is narrower, so a PF30 BB has wider cups that correct for the length of the shimano spindle. I really like the Wheels manufacturing BB's that actually thread into one another.

Thanks Beston.
Not as easy as I hoped, but I can at least keep my bigger big ring and power meter.

Dan

Just to close the topic - got the PR3 and took in my own crankset when buying and asked the shop to fit it before I pick it up...

Easy, new PR3 with full Shimano now and a PM

Dan