I would definitely download it and take it for a spin :) As for pre-populating, you could also offer a save file. Like a “Tumblr Special” where you can ask your followers for families or pick 10 people and request families via PM/Ask.
I think it would be fun to use other people’s sims for this for sure. I think your idea would be the best way to go about it. I have to look into it more, after doing a bit of research on it it’s not as easy to populate a world than I thought it was. :p
I would definitely download it. You can do whatever you want with it. Though I’m wondering what other EPs were you planning on using?
Eventually I’d like to get all the EPs and SPs. Like I said, definitely Generations. I would like to upgrade to Generations now, but in all honestly, the only thing that’s holding me back is fear that it will break my world. XD