The new Steel Fist swiss pikemen do scale very nicely with Perry miniatures. I've got some but have yet to paint them.
The Foundry range is indeed a bit 'cartoony', just a different sculpting style. I have mixed a select few into my mostly Perry collection though - I find the ones with visored or closed sallets work best, as it hides the 'distinctive' faces. They are overall a a bit shorter and chunkier, and some of the poses are a bit odd (floppy arms?).
Example - the halberdier in sallet and mail on the corner closest to the camera is Foundry, most of the rest are Perry.
And the same unit from a different angle -the captain with the sword is Foundry, and actually one of the all time favourite miniatures in my collection!