While not helping you exactly, I would recommend you try the Scarpa Freney XT. I tried the Nepals but their heel doesn't fit my foot, so went with Scarpa. The Cumbre is similar to the new Mont Blanc, so I can hopefully help with this comparison:
Size 43.5 Scarpa Freney XT
- long and narrow fit
- quite well insulated (been in -30 no problems)
Size 44 Scarpa Mont Blanc GTX
- wide and short fit
- less insulated than the Freney
The long and the short of it, is that with the same socks, same feet (mine), I needed different size boots from one company to fit me properly. Both are fantastically comfortable and climb exceptionally.
If the Cumbre / Mont Blanc didn't fit you well, try the Freney. It's a much tighter fit.