You need to realize that with hardware accelerated stuff everything is fine until your configuration "fits" into available features, as soon as you need something outside the provided set of features you are screwed.
I had experience with other equipment that provided hardware NAT acceleration, all look beautiful until problems started - in the end it turns out hardware NAT supported only 1000 connections....
Statement about 1Gbps TCP it is only for 1 TCP connection, i'm pretty sure that qwith 10G connection you will have much more tht 1 TCP connection
in any case i will have to agree with previous poster - "NAT with 10G connection" is not enough information to answer your question. We need to know full set of features you plan to use and actual max available traffic to provide some educated guess.
With great knowledge comes great responsibility, because of ability to recognize id... incompetent people much faster.