Well, I don't think you will have any detrimental effects on your body, I'd say it'd be a nice change.. .and good refreshing workout. Some might tell you of the catabolic effects of long endurance cardio... but if you stay on top of your diet and training, you should be ok.
I'd stay off road running... it can cause shin-splints very fast... unless you are really used to it...
C-ditty