Redshift Shockstop stem setup

I've just fitted a 70mm Shockstop stem to my gravel bike. First ride I left the stock elastomers in as they were what Redshift recommend for my weight. I could feel some benefit, but it was a bit marginal apart from on bigger hits (rough fire road). I appreciate it's not a suspension fork...

I've fitted the next elastomer down and now there's a little sag when sat on the bike; does anyone with experience of these have any thoughts as to whether a few mill of sag (and feels like more movement on a (steep, fire road standard) driveway test) is desirable or am I just thinking as if it's a fork?

An indoor push down test with the stock ones gave only limited movement - now there's much more, but how do these things bottom out? I don't ride much singletrack type stuff on the gravel bike - mainly fire roads and rough back lanes etc.

Last elastomer suspension I had was a Manitou Sport fork *ahem* some time ago (ie last century!)...

I guess the proof of the pudding and all that, but interested in the experience of others.