In reply to mlmatt, davey_briggs and fredt:
You really do surprise me. I had a full set of hexes when I started climbing and for a while I used to use them; then I realised that the number of placements you actually need them for (especially since the advent of No.11 walnuts) is very small if you have a full rack of nuts and cams.
Of course there will be an occasional placement that a hex is useful for, but the benefit this gives you is VASTLY outweighed by the effort of carrying them up a route just in case.
The argument that a beginner may be better off learning with hexes than cams is perhaps valid and something I hadn't considered - but they should find a friend to borrow some gear off and learn how to use it with them if possible. This to some extent is what I did - but I certainly think anyone climbing with hexes who has any experience and climbs above HVS-ish is missing a trick. And all the people I climb, I'm pretty sure, feel the same way.