The flo liner is meant to stretch in the toe area, like the higher-end ski boot liners I've seen. There are three liner sizes per shell, and the ones with larger numbers are presumably the same length, but thinner, so there's more room left for your foot. I have had a few sizes and this seems to be true, but am not a UPZ expert so who knows.
If you're going Intuition, have a look at Intuition Pro Tongue liners. They don't have the thick foam on the sole to take up all the room. And they have the neoprene toe area like the flo... They may fit a size smaller shell; that is, you could maybe size up without crowding.
Basic idea: get the shell right, then mess with liners. Sounds like you have the right shell, but aside from what Dan says, how is the shell fit?