i like what freeskiing youth said about bootfitting in terms of the zeppa, and the booster straps, but i feel he's not going into the flex of the boot enough.
Being a bootfitter myself i will agree with everything he said, but would like to add a bit.
When you try on a boot, buckle it down, and flex foreward as hard as you can.  if you feel a dead spot or pressure from one of the buckles....  the boot doesn't work with your body.  don't buy it.
the dead spot is usally caused by a buckle, but can also be from the boots lack of flex with you.  trust me you'll feel it.
the other thing to look for is the cuff of the boot fitting your leg.  when you flex foreward, make sure your calves don't come off the back of the boot.  if they do, the boots are too roomy, and you'll get shinbang too.
just because a boot fits lengthwise, and around your foot, doesn't mean it will fit your leg properly.
you can actually ski a stiff boot if it fits you well and flexes properly with your body.
I do however swear by the full tilts, because of their natural flex, and wrap around liners that totally fill up the volume of the boot.
the other thing is that boots can be punched and ground out, and are designed to be.  this means go with a boot that is a hair too narrow, instead of a boot that is a bit wide.  you'll get a way better fit out of the boot in the long run.
I've been rocking the konflicts for a full season now, and on the shell fit, my feet touch the sides just barely.  thanks to a custom foot bed, and the very high quality intuition liner  (full tilts is a step above the other intuitions...  it has a different layer of foam)  my feet are very happy in them.  i've never once gotten shin bag from them either.
but really pay attention to the flex.  and just make sure you don't get your boots too big.