Honestly, I don't worry much about the mash-out. I have to heat my sparge water to something, and 180F is as good as anything. It begins the process of halting conversion, but heating the runnings finishes the job faster than a mash-out step will do---without the risk of tannin extraction. So, I don't worry about actually getting the grain bed above 168F. As long as the grain bed gets HOT, the kettle will finish the job.
Stopping conversion is desirable because your mash profile has created a certain fermentability in your wort. Ultimately, this controls the final gravity that your finished beer will reach (along with yeast selection). If you go to the trouble of mashing at 157F, with the idea of creating a full-bodied beer...then you don't halt conversion...the enzymes will continue to convert those dextrins into maltose...ultimately drying out the beer below what you had intended.
I do not have a herms or rims system. I think about it every once in a while...but, I can control my FG using mash-temp alone to within 1.002 SG (0.25 Plato). Generally, I hit my desired FG dead on. I mash-in 2F above my target mash-temp. I generally lose 4F during the full hour. So, the average mash-temp equals my target. If I lose more than 4F (in winter, only), I'll pull a small decoction to bring it back up to my target.
So, really I don't know what a herms or rims would actually do for my beer. For the few beers that benefit from a multi-step mash, decoction does the job without THAT much trouble.