@JALxml thank you for all these details, it is really valuable information which I’m certain will be helping a lot of people. Your chart is also showing most likely why I’m fine using the +1 in the headset where otherwise I’d need +2.5 at about 40cm!
Here are the glasses I’ve purchased so that it gives you an idea of their size and shape:
Each glass is about 5cm x 4cm:
They fit perfectly into the G2 and I’ve chosen this model because I can unscrew the frame and release the glasses easily should I want to make my own “cheap” inserts (VR Optician is about 6 to 8 weeks long).
NB: they are not the most comfortable to me, especially at the nose and I need to further take time adjusting the pads. I’ve also in the past and unrelated to VR tried the Costco ones (very cheap pack of 3) but they didn’t came close to the Foster Grant cheap ones at the drug store. I also have others Foster Grant cheap ones for day to day use (when working with tools and such, I don’t risk to scratch my regular ones) and I must say this +1 model has neat optical properties edge to edge.