This is a tricky question. I moved from a 170 to a V1U and I shoot weddings too, so I feel pretty qualified to answer it.
Why tricky? Well, mostly because the low-light ability is a HUGE change. You need to have a plan to deal with that if you're thinking about the V1U. It typically "sees" the room the same a human eye does.
That's good. That's reality. That's a perfectly fine camea. It's also much darker than the 170. You've probably shot in dark rooms with your 170 and made the video brighter than it actually was. Those days will be over if you get the V1U. A light will be needed in dark situations. That's pretty much all there is to it.
BUT, the V1U puts out a stunning picture, even when not doing HD. I shoot and edit in HD, but then down-convert to SD-DVDs or the web. In every case, the picture I get now is much better than what I used to get.
Here's a 24p stage show, shrunk down for the web:
http://www.redfeathervideo.com/24/
And here's some wedding stuff:
http://www.redfeathervideo.com/weddings/samples.html
I think the wedding clips are all converted down to 12 fps for web-use, so ignore the slight stutter. What you CAN see there is the sharpness and color and overall quality. Note the 'toast' video. That's with a small camera light, some gain, and some post-processing computer brightening. You could easily beat that in-camera with a 170, but I have to work hard to get that same look now.
So I'm not sure I can tell you one way or the other. The V1 is going to be more difficult and it's going to NEED lights in dark places that you didn't before.
But if you can make it work, you'll make some awesome picture. I make 24p widescreen DVDs and they look fantastic. I still have my 170, I thought I'd use it for simple jobs that don't need anything fancy. Well, I have NEVER taken it out and used it since I got the V1U. I love the improvements too much to go back.
So hopefully that gives you some insight into the 'pros' and 'cons.' It's worked out for me, but I wouldn't suggest it for everyone. Feel free to ask more specific questions if you like. I still have both cameras and compare them head-to-head if you need to know anything.