Hi Austerity, I also use Shadow defender. I use SD for testing programs only and Sandboxie for security but I can tell you that both programs can be used at the same time without problems and you can use SD for security also. Its really your choice. I prefer to use SBIE on its own but it doesn't matter, both programs are good. Sandboxie is a little more convenient and have more settings available, some of which can be used to block programs running in the sandbox from having access to your personal files and folders. Also, Sandboxie is great to protect your system against rootkits. Most rootkits install drivers and Sandboxie does not allow drivers to be installed in the sandbox.
Settings in Sandboxie can be used to do many things, like for example, you can set your PDF reader to be the only program that runs in your PDF sandbox and block all programs in that sandbox from connecting to the internet. In my personal case, the only time that Foxit (my PDF reader) ever runs unsandboxed and connects to the net is when I update the program. You didn't mention any PDF reader in your list but you are probably using one. Its a good idea to sandbox all PDFs that you run in your computer.
I hardly ever download pictures and its hard to encounter a picture that's infected. But it can happen. And when it happens, you ll get a bad infection. So, any picture that I download, its run sandboxed. Its done automatically, I don't have to even think about it, I just do it.
Videos. In the many years that I have used the internet, as far as I know, I never downloaded a malicious video but sometimes video players are exploited. So, by sandboxing my video players, if I ever click on a bad video, no problem, all I ll have to do is delete the sandbox. Look at the video about SBIE Vs Cryptolocker that I posted earlier in this thread. Thats how Sandboxie works against malware.
USB drives. I have a rule that I strictly follow. I never stick anyone else USB drive in my computers but for you guys that do, specially young guys and ladies in school that do that all the time, sandboxing your USB drives is a great way to protect your computer from getting infected. If you do it, and your friends USB drive is infected, you will not get infected, unless you recover the infected file to your PC and execute it.
I have a rule and for me is easy to follow. Any file that goes in my computer, its gonna run sandboxed until the day it gets deleted. I don't care what kind of file is or where I got it from. Earlier in the thread, I posted a picture that shows most of my sandboxes, not all of them fitted in the picture but take a look at it and read the name of the sandboxes. By reading the sandboxes name, you ll get an idea of their purpose and how I use SBIE.
Bo