PR1.2 is out in two weeks and the N9 is quite capable to stand on it's own as it is now imo.
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Anyway I'd always choose the N9 over every other phone because this is one of a kind. Since Elop killed Nokia's MeeGo efforts there won't be another MeeGo phone from Nokia.

As for Android, well you buy your SGS2 and in two months time 20 new Android phones just appeared on the market without any significant differences. What I'm saying is the you won't miss much if you skip an Android phone now, it would only get one update anyway, and you can always buy one later. You won't be able to buy an N9 once it's out of production.

Same applies for WP7. You used one, then you pretty much used them all.