Re: 7mm holy grail
I have a 7wsm in short action using alpha mags and have no problem pushing the 180gr Bergers faster than 2950fps from a 28" barrel.
7wsm brass is available at the large sporting stores in town most of the time. I've never seen any store with 7saum brass in stock. I conceive that saum brass may be better, but it is very difficult to find in stock anywhere, and is much more expensive.
I bought 7wsm in bulk, weight sorted them and neck turned with excellent results. If you want better brass you can use 270 or 300 wsm norma brass, but I haven't found a need to do that.
The whole barrel life vs powder efficiency argument is a wash to me, as if you're pushing them at the same speed it will be very similar. Plus barrels are expendable, and a trade off for better ballistics.