I love both versions of Rive Gauche, the original and Intense. I purchased the intense version as I found longevity on the original very variable - on days it would feel again after a couple of hours, whilst on others, I could get notes wafting to me throughout the day.
I really love the Intense version of this great scent, but to me, it is mainly patchouli that is the difference. I love patchouli but, at the same time, I do feel the Intense loses a little of that barbershop accord of the original.
If it is the barbershop aspect of the original you seek, I would say to stick with the original. If you want the original with lots of extra patchouli, the Intense will work.