Please make sure you've decrypted them. The IPA files iTunes saves to disk have DRM and will become useless once Apple shuts down the relevant servers.

Is there any way to do that without a slow copy back and forth to a jailbroken device?

Not that I know of, sadly. But bear in mind it's only the executable file that's encrypted, the rest of the ZIP file (the .ipa) doesn't need to be copied.