Get the titanium version (half the weight of the steel version), get the down version (half the weight and half the packable volume of the synthetic version, hence smaller and lighter backpack) and get the most reliable highest performance kit (not necessarily the lightest) you can afford for the weather and terrain conditions that you can expect so you don't need a backup or a backup to a backup.

The quality of the backpack and its ability to move with the hiker whilst keeping the load stable and the load bearing ability on the hips is also important. Most UL packs are lacking in this respect. The extra 1 or 2 lbs in additional weight for the pack might be very worthwhile for long term comfort.

The cooking and sleeping systems need particular attention. For example a gas cartridge cooking system will be lighter and higher performance than an alcohol stove if the time out in the wilds is greater than 2-3 days.

For shelter a lightweight tent might also be the way to go when compared to a tarp or basha/ground sheet/bivi bag combo as the differences in weight could be very slight especially when considering the weather performance difference.

Much will be dictated by the terrain and the weather conditions.

http://www.youtube.com/watch?v=73KKZDhoj_0

And sometimes you need a really good tent to cope on a blustery rainy day.

http://www.youtube.com/watch?v=r4NN3cltuuY