Yes the 12th is a difficult hole. On the card and in pictures it probably looks quite easy, but as you said its often into a head wind (Harborne is quite a windy course at times) and the Ideal line is over the edge of the bunker, it doesn't take much for a a drive drift OOB on a tight line. The approach is to a very narrow green as well. I think its a great hole. 11, 12 & 13 are where you can lose a very good score.
I played the front 9 early this morning, considering the downpours we've had at the end of last week the course was reasonably dry still.
I have yet to receive my copy, but a 5 or 6 seems about right to me. I think its on a par with Edgbaston, but perhaps slightly behind Beau, Whittington Heath and Enville. I Don't quit get the love that everyone has for little Aston, but Ive only played it once, so perhaps i need to go back if they ever lower the green fee :-)
Mat