In reply to Ron Walker:
Hi Ron!
Just seen your post and mrjamesdawson's above!
To update, my issue was that my right boot fit nigh on perfect, although tight over my instep and my left was essentially crippling my foot. To the extent where I was certain I either had a bad left boot or one that was incorrectly sized as the fit was so different.
I had both boots punched out just in front of the hinges which remedied the crippling issue on my left foot, but has also altered the comfort when in walk mode and skinning. The toe box for me is fine and didn't need any adjustment.
The result, well the higher instep shape is now so that the edge of the shell digs in to the area above my ankle, through the liner, as I flex forward. I also have a tiny bit of heel slip when making deep movements in walk mode or edging with the toe of the boot (not ideal for crampon work). But this is hardly noticeable when skinning as this movement isn't aggressive enough to induce it. The only other issue I noticed is that in ski mode there appears to be more stress on the hinge as its now slightly further out than when manufactured. Pushing my weight onto it, I can see the outer side of the boot flex considerably, so it will be interesting to see how it goes regarding durability. But I don't think I ski hard enough for this to be an issue.
The work done in the shop was great, they weren't so familiar with the boot and most people seem to get the toe box done, but they tried and did a good job. I was worried that the gaiter rand (the matte rubber bit) would melt off, but it seems to be ok, although has a thinner and slightly wrinklier texture than when new (this is really close scrutiny). There was no effect on the internally glued parts either. I think the thinner grilamid shell has helped in this regard.
On the whole I'm pretty happy and have had no real issues using the boots for touring since. I haven't got around to trying them climbing following the adjustment, so I'm curious to see how (or if) this has had an effect on their stability in technical terrain.
Alternative remedies may be to remove the insole and replace with others that are much thinner. I found that pre-punch and liner moulding this helped a little (but not enough) with relieving pressure points over my instep. The most common remedy for liner issues that I keep hearing is to go with intuition liners. But you need to be careful with sizing as mrjamesdawson mentions!
Hope this helps!