I have the edge 305 with HR and cad and once you get used to everything, it is wonderful. There is a part of me that wishes I had gotten the forerunner though. I do a lot of running as well and I think it would have been a little more beneficial to me. Check Garmin's website. They have a list of features for each model. You may wanna pay attention to what bike specific functions the forerunner is lacking.
~Nick