Two points to add to OS's comments ..
(a) the gradient vs speed graph is pretty flat .. while the absolute best gradient may be a reasonable bit above V2min, there is no point worrying about it on a simple cost/benefit basis .. the main thing, as he observes, is that you get a comparatively big benefit at little cost if you peg modest margin above V2min.
(b) as another poster observed, there is a consideration with escape procedures. If a turn is included, then the procedure designer will have done the splays on the basis of a min/max V2. As the turn, typically, is to miss a hard bit, you need to make sure that you are NOT above whatever the maximum V2 published with the procedure might be. If there is no published max V2, then look up the V2 for the max published RTOW on the procedure and that is the max V2. If OM SOP doesn't clarify, check with your designers as to whether the turn radius included the V2 overspeed allowance for high weight takeoffs.
OS ... you going to BrizVegas ?