Monkeybrain: looking at the photos, it seems impossible to fit the US grip underneath the European grip, so one must come off to fit the other.
Imaging Resource has a photo and some more info on this page (search for ‘Custom Grip’):
www.imaging-resource.com/PRODS/canon-g1x-ii/canon-g1x-iiA.HTM
They say the bulbous grip will be sold as an accessory in the US, so it must be user interchangeable.
I still don’t know if the European camera will come with both grips in the package, or just the bulbous one. If the latter, there won’t be a way for Europeans to get the US grip, since it won’t be sold as a standalone accessory.
I will never understand why companies leave people guessing about this kind of thing. All it takes is a line in the press release or brochure.

Started out doing photography at the age of 6 using an uncle's old 1940 kodak brownie box camera. At 15 years of age, I decided to buy my very own 1975 Praktica SLR camera. I now shoot with a Nikon D850. I do unpaid TFP and commercial paid work.