Looking good there pseud, keep up the good work!
Great find on the driftwood, I've only used Malaysian driftwood in my tank, and I've really liked the ridges, nook and crannies, and colour of all of the pieces I've bought. More than that, I feel it balances out your aquascape, as like illusion54 said earlier, I too felt that using just that one piece on the right created a sharp, attention catching division of your tank.
The tank will really look better when the giant hygro (?) and Lobelia cardinalis in the background fills out. The Elatine triandra and Nymphea Zenkeri in a couple of months time should look fantastic, although I think moving the Nymphea Zenkeri to the front a bit and making it more prominent.
Also would be a good idea because it wouldn't shade the plant when the Lobelia cardinalis grows, IMO... But more importantly, the position its placed in, its already following the golden ratio, and since it is a red plant, it will only add to being the focal point of your tank.
Good idea on removing the Cyperus helferi, I felt it did nothing for the aquascape, and perhaps, even detracted from it. Did you remove it because of the algae? I'd also lose the Vallisneria Spiralis, as I think it would look out of place in a couple of month's time when your tank matures... It might also detract from the Nymphea Zenkeri, JMO.
All in all, great looking tank, and you obviously know what you're doing. Tank will look even better when it matures, so good luck and please keep us updated with pictures...