Barit1, I agree that if you are very close to the runway you wont make it.
But still if you are max flexed, your climb gradient is higher than your gliding angle. Check your books. Most modern airliners have more than the needed 4-5°.
For a turn you need 2 minutes that means 1-2000 feets. You still have a little excess speed from climb out speed to best gliding speed. You also want to bank a little more than 30°, the faster you turn the faster you are on a inbound heading.
Checking the ILS: Means tune on your ILS (opposite direction) when climbing out. You will see if you are above a 3°. Do it every day and you get a feeling of how good you climb is on a average day.
Sorry, my thinking is not hindsight. I have tried this a few times and we have done it in the simulator (before the Hudson accident). If you don't like my reasoning, then ok. I just want to give you a set of tools. I'll promise you: The next similar accident will not turn out as well as this one, because ditching is a very dangerous thing, and they will not make it successfully. Everyone today thinks that ditching is the first option. It is not! It's the last.
Dani