I am creating a standalone-application (as portable). No installation and registration of components. From external files I only resources (language files and images). But while I use 7za.exe to work with 7z-archives

But it is an external application, not a library, and it does not have the ability to manage. The result of the application only error code. Implementation progress either.

While there is no desire to link VszLib.dll, since added another library to 7z.dll
Source code is accompanied by more difficult as you need to edit VszLib to add new features. Distribute the application will be more difficult as the final version of the library on the client side can be different