Most upgrades I've ever purchased, required proof of purchase of the earlier version in order to activate the upgrade. I'm not sure how Avid has decided to handle this. You should just ask them, it's a perfectly legitimate question. My gut would say no, as you saved money by doing the crossgrade that other purchasers of PT 9 didn't have access to. The other side of that is that those other people also didn't shell out money for PT 8 LE. It's probably a bit of a gray area, but I'd find out from Avid before making that move. That could end up being a rather expensive mistake if you ever have to re-install PT (and you know you will).
What is hip?
Gear: Digidesign 003R / Telos Zephyr XStream ISDN codec / JK Audio Broadcast Host digital phone hybrid
PC: HP 6005 Pro MT PC running Windows 7 Pro 64-bit w 3 GHz AMD Phenom II x3 B7, 4GB RAM
DAWs: Sound Forge 10 Pro, Vegas Pro 9, Adobe Audition 3.0, Pro Tools LE 8.04, Reaper x64.