I have sort of mixed feelings about helping eggs. The day after Christmas I opened a bantam cochin egg that had pipped and then nothing for 16 or so hours and the result was a vigorous healthy chick who is no different from the rest, Im not even sure who it was anymore.
On the other hand I opened a pekin egg this past spring and the results were less then encouraging. It was the last to pip out of 15 or so eggs that all hatched fine. 24+ hours went by and the duckling was still peeping and rocking the egg and having more eggs that had to go into the bator I decided to open it. The result was a partially blind duckling that I had to hand feed, take to work with me and was generally a pain in the neck (I didnt have the guts to cull back then but since have). She lives as a normal duck now with 2 other ducks that have become very bonded with her and it has worked out like a dream but given the choice again I wouldnt have opened that egg.
I guess its a risk that you have to be willing to make.