I rate myself as an expert :-) in sole comfort as I have a significant disability which gives me forefoot grief. I use Scholl Gel Sports insoles (the blue ones.) Although they can be destroyed I have found that if I put them on top of another thin sole, like the original insole, they have lasted. I go for a larger boot than usual as there's more toe room and can stick two soles in if I wish.
Historically gel soles can get damaged when they move around inside the boot so after river crossings or if I feel any discomfort I check that they're still in place; so far so good. $40 a pair but better than limiting yourself to short days and crippling pain.
I also have invested in Stoney Creek Greywacke boots as these are by far the softest/thickest forefoot. Not a mountaineering boot but still pretty stable as they have a high upper. For example, I have gone from 5 hour days before these boots to 8 hour when wearing them.
This post has been edited by the author on 2 August 2018 at 15:47.
Do you still have the old boots? Have a look to see what the differences are and figure out how to resolve them. It might mean going back to a new version of the old boot. One thing that might work is a layer of snow foam as an insole if it will fit in the boot. Generaly the softer the boot the more comfortable but the less suitable off track. I dont know how true this is but I know my 3/4 season boots give me ankle ache on a long hard surface walk. I now wear gym shoes of good surface tracks for Sunday walks which helps a lot. Little or no risk to the ankles on those tracks. You cant put crampons on a soft boot
The above guy doesn't have an invested interest in orthofeet at all hahaha.