Vietnam Squad Battles games

[Paul]

I was thinking of using the upcoming JTS sale to dip my toes in the SB games, Vietnam being my chosen period. Any tips as to which of the two titles to buy (or indeed should I get both!). I believe  that to play the North Vietnamese side I need Vietnam rather than Tour of Duty.
For anyone who has played Vietnam 65 how do the two games systems compare. I have played games from both JTS Panzer Battles and Campaigns.

Thanks
Paul