Nobody can answer the question definitively because they don't have your rifle. I would say to take advantage of the fact you can buy different brass in small quantities to make some assessments of what works best for you.
I'll point out that Federal, whose commercial match ammunition has a good reputation, still works with IMR 4064 in the .308 versions. I don't think Vihtavuori is necessarily magic in this regard. IIRC, it's nitrocellulose is made with 100% cotton cellulose rather than wood or other more resiny sources, and I think they make their own nitrocellulose and nitroglycerin and deterrents and stabilizers to get a higher grade than is most often used by other makers. This results in relatively clean burning, but at the end of the day you still need to clean your guns, so whether that is a significant factor for you or not depends on your shooting patterns. When it comes to powder, I would consider every source and go with whoever makes what the gun likes best, regardless of the source.
If a gun is not shooting well, there is usually some dominant error source that has to be dealt with, whether it has to do with the load or the mechanics of the gun, and until you find it, your load tuning steps can often appear futile or to do very little. Once you do find it, though, then things you tried before that didn't seem to affect group size, can start to make a visible difference, so you wind up having to check them all over again. The other approach, and one I use, is to make the loads as perfect as possible initially, with every kind of sorting for consistency and brass prep I can manage and load assembly I can manage, knowing some of it is a complete waste of time. If I can't find a tight grouping with a series of loads built that carefully, I know I have a gun problem and not to waste more time in the load search before I find it. But if I get a tight shooting load, I can then drop back and eliminate some of the careful load assembly until I see what matters to that load and what doesn't.