In theory, I love the idea of facedown cards, but in practice, unless there are several facedown cards with identical costs, everyone will always know what the card is anyway. Imagine if every element got one facedown card... well, it wouldn't take much to figure out where that 3
went to if this card were played :p Fortunately, by making the unupped and upped cards quite a bit different, you've mitigated this problem to a certain degree, and I applaud you for that.
If you look at the CCG Netrunner (the original) with its hidden card mechanic for the runner and hidden cards for the corporation, or MTG's morph mechanic, you'll see that you need a fairly large series of similar cards before it really works.