Foam injected boot liners
Sounds like you're basically on the right track. Once again, I agree with coppernyc. It would probably be helpfull for you to check into the "Boot fitting expectations/ettiquette" thread that was started on 8-16-04.
The more time you're in boots, the more absolutely crucial it is to eliminate problems. I'm a tight boot fanatic and a "challenging fit" myself. After an often painfull several year struggle, I switched to foam injected liners in 1992, been in them ever since. I'm not sure how long, but foam injected liners have been around awhile. They were good 12-15 years ago; even back then, the foam was a drastic improvement for me. Nowadays, the earlier problems have been addressed, they're even better, and a little easier to have installed. I'm now in my 3rd pair of extensively re-worked Salomons with the Conformable foam liners. For me, it's the only way to fly.
There are a number of advantages to foam. For one thing, since the foam will conform to almost any shape, you have somewhat more latitude in shell choice - although obviously, in the first place, you still have to pick a shell that's a close match to your foot shape and ability level. This critical first step is deceptively easy to go badly wrong without highly objective professional help.
The foam essentially does for your entire foot and lower leg what a custom moulded orthotic does for only the sole of your foot. The more even pressure distribution allows a tighter, firmer fit than a conventional liner, eliminates slop and enhances sensitivity, feel, and overall control. The more even pressure (to me at least) seems to be less constrictive overall; better circulation; warmer feet. The insulative properties of foam were slightly inferior up until about the late 1990's, but that's been completely resolved; if anything, the newer foam compounds are warmer. Also, I've found over the years that the foam is definitely more resilient and doesn't crush and pack out nearly as quickly and easily, which means significantly better durability. So once you've undergone the hassle and expense of new boots, you're all set for a good long time. Mine have been good for 300 to even 400+ days.
Fitting and installing foam is a bit of a technically tricky business. I've found them to be a Godsend, but they're only as good as:
1. You preparation, in terms of patience at working with the fit tech person - this isn't always a quick and easy one-day process.
2. The saavy/skill/expertise of the boot fitter tech people.
3. Your honesty with the above person regarding self assesment of your skiing strength/ability level. In other words, even a perfect fit in too much boot will detract from your control.
Surefoot is a good bet, especially if you're in the east and planning on doing extensive traveling to ski.
The only relatively minor disadvantage that I can think of is that since foam has to be done professionally in a specialty shop, not in someplace like a big sporting goods chain store, it's more expensive. It isn't really neccessary for everyone. Again, I'd recommend taking a look at that thread from last month. Hope this helps some.