Having worn my G8’s a number of times, I haven’t yet been successful at nailing a comfortable position. I am still changing between different height options and positions regularly in order to find a comfortable position, although I am finding that it’s a bit of a compromise. By that I mean having the arch support further forward does relieve some pressure off the ball of the foot and big toe, but tends to result in an uncomfortable feeling out of the saddle, almost like my foot is rolling forward and outwards and I’m unable to ‘flatten’ my foot properly. When they are further back I have more pressure on the fore-foot again (leading to the usual hot-spots) but then it’s a bit more comfortable out of the saddle. I am also finding that a position that feels ok in my mountain bike shoes doesn’t feel right in my road shoes and vice versa.
Taking the pressure off the big toe and your mid foot will help alleviate hot foot. Basically, many variables come in to play in order to establish the best position for your insoles. A common theme we are seeing with serious cyclists is damage to the muscles in the bottom of their feet. Due to being tied down in a hard soled shoe, the muscles over time are no longer flexing, lose strength which in turn fails to support the foot correctly. This is similar to why elderly people lose height as their muscles supporting their spine become weak through lack of use and no longer support the vertebrae.
Most cyclists cannot point their toe and arch their foot without some element of pain and discomfort. A number of cyclists I have seen can’t jump lightly onto a 60cm box either which is related to the feet (unless they have really tight hamstrings then it is both).
From what you are describing I am guessing you fall into this category to some extent. This issue can only be fixed over time. The flexible arches will help but it is a bit of a rehab process. Wearing toe socks and going barefoot may also assist.
Out of the saddle – This is also related to weak arch muscles. Because the muscles have not been worked for some time they do not have the strength to pronate within your shoe. Suggest you try a lower arch and work up. Again this will take time. You may have to forgo some hot foot issues until your arch strength gets on track, although a low arch piece will still help.
Shoes – every shoe is constructed differently and therefore the G8’s react differently within the shoe. Especially with the way you are describing your feet, they are going to be more sensitive to minute changes of pressure within the shoe. Mountain bike shoes usually have more room to allow your foot to move as well.