It gets SO much more complicated. I'd put builder quality ahead of material, honestly. I am a smooth and light rider and I destroyed a ti frame in about 500 miles of XC riding (read: no jumps, no silliness, no abuse - yes, JRA). The frame was broke at the down tube and had a serious crack in the chainstay - seatstay junction. I'd take a good steel bike over that heap any day of the week. (I'd take a skateboard over it)
However, my Black Sheep was made by someone who knew what they were doing in Ti and its VERY compliant in the right places and rigid where it should be. The price is jaw dropping at first but if you know what kind of bike you can ride for the next 10 or more years its really a great value.
Do a little google-ing on the last SSWC in New Zealand. It was a short helicopter ride to the local high end aerospace shop to get a ti bike repaired. No worries, mate!
Make it simple you say? I'll throw in a vote for Ti but I don't think you can go wrong with a proper steel bikes either.