I've been on both apps since Cubase SX1 and Nuendo 1.6. As I also do music productions only, I am thinking about going the Cubase route too.
I didn't bond with Nuendo 5/5.5 as I did with the earlier versions (for some odd reasons + some GUI things). Besides, it is a waste of money (on my behalf) to maintain and upgrade both paths.
The Control Room is there in Cubase 7 (also C6 and C6.5), no worries there

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If you use many of the advanced automation features in Nuendo you may miss some in Cubase. The preview function in my case, but I'll live.
The 4th mixer is not a big deal, but some times has been good to have (this might change with the new Mix Consoles).
Not much else from my, a music only producer's, point of view.
As for me choosing Nuendo before Cubase (Nuendo in studio, Cubase at home), has mostly to do with what to me "felt" like a better GUI.
With Cubase 6/6.5 and Nuendo 5/5.5 this came so close that it was not an argument anymore.
And the whole NEK thing discussion will never end (what a clumsy idea). The only difference in the upcoming Nuendo 6 is that the installer is included (but 100 Euro more to upgrade).
All this together will make me choose to put money in just one of Steinbergs pockets, not two. Cubase is coming on as the strongest contender, with exceptional value for money.
Sorry for ranting

. Hope you got some answers
