I have LR 4 installed and consider trying out LR CC (testversion for 30 days). If I want to switch back to LR 4, can I downgrade back to my installed LR 4? Any problems with this?
Lightroom CC will be installed in addition to your Lightroom 4. When you first start Lightroom CC it will prompt you to upgrade your Lightroom 4 catalog. If you choose to do that, all of your work that you have done previously will be brought into Lightroom CC. The upgraded catalog will be in addition to your original Lightroom 4 catalog. So Lightroom 4 will be left alone and intact and usable. Any work that you do in Lightroom CC that is in addition to what you had previously will be in a catalog that Lightroom 4 will not recognize. However, those new images will still be on your hard drive and you can import them into Lightroom 4.