Janet Evans was and is wonderful and I have her book Total Swimming - a bit of borrowing there, perhaps? Her stroke is totally individual, though, and definitely not to be imitated. Amazing head lift on breathing stroke.
David Davies (of Wales, not England) hasn't actually swum under 15 minutes yet this year, so in fact only four swimmers have done it. He did do 15:00.73, which is as near as dammit but not quite near enough and nowhere near Sun's record time.
The US trials are coming soon. Will we see a sub 15 minute 1500?