I currently commute from grove street to Princeton by train. There are some express trains in the morning, and the PATH and NJ transit trains at Newark are well timed, so I can get from the grove street path station to Princeton junction in about 50mins to 1hr. I'm all for the train, as unlike the car commute, you can read/nap/work/whatever on the train. Its definitely doable though. I'd recommend living as close to a PATH station as possible.