It won't really slow you down, for sure. I think the only time the flex is an issue is descending, but if it gets hairy you can just knock the pace off a bit and take it easy, and I think you'd have to be pushing pretty hard to get to that point. I just find the ride of the 631 Vig a bit agricultural compared to 'better' steel frames I've ridden. Perfectly usable and not uncomfortable or anything, just less polished.
It won't really slow you down, for sure. I think the only time the flex is an issue is descending, but if it gets hairy you can just knock the pace off a bit and take it easy, and I think you'd have to be pushing pretty hard to get to that point. I just find the ride of the 631 Vig a bit agricultural compared to 'better' steel frames I've ridden. Perfectly usable and not uncomfortable or anything, just less polished.