Answering my own thread, I've now decided that the Freedom Universal Bluetooth Keyboard is indeed exactly the same keyboard as the iGo/Stowaway Bluetooth Keyboard for Blackberries (AKA Shasta). They certainly look exactly the same in pictures, have the same specs etc (apart from one working only with Blackberries, and the other having drivers for everything).
So, I found this set of reviews at Amazon:
http://www.amazon.com/gp/product/B00...Fencoding=UTF8
A mixed bunch. Basically it seems to be saying that physically it's a good quality keyboard, although the lock holding the keyboard open (for knee use) is a bit flimsy. The drivers seem to be poor, although by definition that doesn't apply to the Freedom because they'd be different drivers. As it happens, though, I've found a (very) few user reviews of the Freedom which says that its drivers aren't great, either. The Freedom is new (new to Freedom, anyway - clearly someone has been making it for Stowaway for a little while), so perhaps the drivers will improve.
I'll stick with my Stowaway Universal, though I do sometimes miss the number row (literally), and generally think the keyboard is a bit more rickety than I'd like.