I've only ever reloaded with vit. I bought the n-130 for .223 as this uses less case capacity than n-135, n-140 is what I use for the deer legal centre fire calibres,but even then n-140 can be used for the .223.
The only use I can forsee for the N-135 is if I were to load up a 125gr ballistic tip in the .308 as it seems like quite a specialised powder,for lighter bullet weights.
I'm very happy with the powders,in the shops I've been in,they have said that it's no cheaper to by a 1 kilo container than it would be to buy 2 of 1lb.
If you can get the pamphlet of vit loads from your dealer for free,it's worth having,I also find it very helpful that the Sako catalogues have the details of the powder loads for their ammunition,which is very good for giving a few pointers. I suppose it must be safe,as it's factory loads?!