It can't be overstated how important the weight of your footwear is. It's been said that every pound on your feet is equivalent to five pounds on your back in terms of energy expenditure. And your average pair of hiking boots can easily weight four pounds, meaning you're carrying the equivalent of a twenty pound backpack on your feet. Given that your goal should be a ten pound backpack, a twenty pound backpack for your feet seems like overkill.
For this reason, many ultralight hikers elect to use trail runners or some equivalent as their shoe. Granted, a trail runner is not going to have the durability of a well made boot, but like everything else it's a trade off. And contrary to what you might think, there are many trail runners that are waterproof, and even some that provide ankle support, though with a light enough backpack ankle support isn't really necessary.
For reviews of various hiking shoes and boots, see here.
When it comes to trail runners made for hiking, one of the best brands is Inov-8. Many of their products have won awards, and they're well liked by ultralight hikers. Many of their shoes come with Gore-Tex liners for keeping moisture out, and they even have a few pairs of shoes that look like full on hiking boots, though none of their shoes, not even the imitation hiking boots, weigh more than 400 grams (14.1 oz). Definitely a company worth checking out for your next pair of hiking shoes.
Another brand worth mentioning is Montrail. Their shoes tend to run a touch heavier than Inov-8's, but too offer features like Gore-Tex liners and they've worn their share of awards too, and are well liked by ultralight backpackers, so definitely worth checking out.