Randy,
Don't know a lot about it, but Liquid Springs appear to be a really major chassis modification---not to mention really expensive as well. Not in the same league as upgrading shocks or individual suspension components (and not a self-installed option for most folks). Bet there aren't a great number of "upgrades". Most of the folks with them got them with new builds.
Mike
Oh yes! I am certainly aware of that. ~10K from what I understand. But just like the ...I hesitate to mention it..
that quiet ac unit...shhhh, usually there are a few early adopters that are VERY proud of the upgrade and spread the word. And 'only' $10 K to improve the ride might be much more attractive to people otherwise satisfied with their coach, over costs to purchase of a new unit/ sale of their old to achieve the same result.
Yeah, $10K to improve 1/2 the suspension, and not the part closest to the Butt Seismograph.

Not on my short list, but still interesting..
I found that one reference in the Facebook group, and know several here are non-FB so I posted it to inform.