I agree that skill levels can make a huge difference in a V-Strom's off road potential, but one thing that isn't going to be affected by skill level is physics. There's no getting around the fact that it's a 500 pound motorcycle (or more, depending on accessories) with only 6 inches of ground clearance (less, with a skid plate), almost forty pounds of fuel sitting on top to make it top heavy, and only about 6 inches of suspension travel in the front and rear. It's perfectly fine for gravel and dirt fire roads, and even smooth singletrack, but in even marginally sketchy conditions you're going to have to work about 10 times harder to ride it than you would an actual dirt bike. In terrain that you could just power up and "float" a dirt bike, you're going to have to crawl over obstacles and hope those roots and babyheads aren't too much for your skidplate and short travel shocks. And woe unto you if you're out on a trail alone and your V-Strom falls over on an off camber hill. Even a TT250 could be a pain to recover in that sort of situation; imagine trying it with a 500 plus pound bike.
If your idea of off road is rough gravel and dirt roads like you find in a national forest, then the V-Strom will do just fine. Even a dirt, non technical singletrack through the woods wouldn't be off limits. If "off-road" means really off road, with deep mud, sand, slickrock, rocks, logs, etc, and especially if you don't have any off-road experience, then I think you're going to end up hating the V-Strom. It's a terrible bike to learn off road techniques on, because off road riding techniques that actually do work on an actual dirtbike could be disastrous if you tried them on the Suzuki.
I don't doubt for a second that a pro MX rider could take a V-Strom and make it do amazing things on some pretty rough terrain. I'm also fairly certain that, if you asked that rider once he was done whether he'd choose to do the ride again on the V-Strom or a YZ450, his answer wouldn't be "pass me the Suzuki, please".
"No matter where you go, there you are."