While I can't say for sure because I have nothing to do with Poser's development, given its track record for being able to open older files, I'd guess yes, you could. However, that being said, that may not work in practice. If I create a scene mostly in 11 and then load it into 12 to add materials using the cycles that weren't included in 11 but hopefully will be in 12, and then I realize I need to run a script say ezcloth for a dress I decided would work better for the scene, I can't. If ezcloth isn't updated, it likely won't run in 12. But if I reload the scene in 11, I will lose all the updates made in 12 that aren't part of 11, like the new nodes.

---

Available on Amazon for the Kindle E-Reader Monster of the North and The Shimmering Mage

Today I break my own personal record for the number of days for being alive.
Check out my store here or my free stuff here
I use Poser 13 and win 10