I have a pile of DUK in my 401K from when they owned the company I work for. I think Spectra has more potential for growth because it will be less regulated that DUK will be so I'm currently leaning towards moving a good chunk of my remaining DUK stock over to Spectra and keeping a small piece in DUK for old time sake (and because I could be wrong). I also see a steady rise in price towards the end of the year when they split the company unless something ugly happens before then.
On the other hand I have a bit of time to decide what I want to do here and I'm not sure how much flexibility we'll have inside the Duke 401K system to move funds between these two stocks.
I've been really happy with DUK to date tho and it has performed as well or better than the rest of my retirement investments. I love the DRIP and the fact you can trade inside the 401k without paying a defined commission (although I assume the costs of this are recovered somehow by the plan administrators - anyone know how this works?).