Kev T,
FYI: My 2016 Band-in-a-Box for Windows UltraPlus Pak hard drive is about 500 gigabytes. I've read that the hard drive for the Audiophile edition is substantially larger.
I can understand your desire to bypass the extra taxes you have to pay to get the program loaded on an external drive versus downloading the content. I would suggest that is a political problem you can address with your politicians but that might give the politicians the idea to tax download content!
Seriously, though I copy the hard drive contents to my computer's hard drive I find the knowledge I have the hard drive as back up to be very comforting.
I switched from a desktop running XP to a laptop running Win 7 earlier this year. I decided to download all the files to have the added security of the downloaded files. It took about 24 hours (spread out over a week or so) to download all the compressed files.
I decided to run the programs from the computer's hard drive. The main reason is if you use shortcuts to open your programs the shortcuts MAY not work consistently. Windows may not always assign the external drive the same drive letter each time it is plugged in. One less thing to worry about.