In my windows phone 8.1 project I am using MediaCapture Api for capturing photo's, but I experienced issue on the devices that comes with 8.0 and later upgarded to 8.1, The problem is that on such devices camera capture fails after taking 10-15 images and it's just saves green screen instead of original image. So what I thought is to create 8.0 class library and use CameraCaptureTask of 8.0. Will that work? If so than Is it recommended way to do so?
Guessing that your 8.1 project is 8.1 XAML not 8.1 Silverlight the answer is no. The camera API really sucks in 8.1 XAML, if it is a core functionality of your app, just go with 8.1 Silverlight.