Re: 7mm STW?
Well, I had both, but not at the same time. My very first rifle for deer hunting was a 7RM. I liked it but sold it to buy a 7STW thinking that the velocity performance would be significantly better in the STW. I was living in the midwest at the time and long dear shots are common.
Not the case for me. As it turned out, it was the ability to launch heavier projectiles, not velocity, that improved. I could launch heavier pills in the STW at nearly the same velocity as lighter pills in the RM. Between the RM and STW, when using the same weight projectiles, velocity increases were minimal at best, 80-100 FPS.
You really need a long tube and slow powders to get the STW to perform at its peak. You also need to be willing to handload because factory STW offerings are expensive and the selection is not that great.
The RM is less picky. Still an over-bored cartridge, a long tube is not as detrimental and there are a lot of factory loads.
My experience was that the extra performance of the STW did not justify the costs.