Welcome ed72,
I think you will find yourself very happy with whichever model you end up with. If you are focussed on dual suspension know that there are none in the current lineup with dual suspension. The first Silvio 1 and 1.5 were narrow tire suspended, 45 degree seat; Silvio 2 through S30 were upgraded to hydroformed (sexier, lighter, stiffer) frame at 30-28-33 degree seat angles; Note that the very last batch of S30 were the ones that did not have the front suspension and had 33 degree seat angle.
It is generally accepted that a larger volume tire (at appropriate pressure) without active suspension compares favourably:
-comparable shock absorption somewhere in the virtually-the-same, the same, or better cush-to-your-tush than the small amount of suspension,
-significantly stiffer front triangle which means better power transfer from pedal to ground,
-significant weight savings which means among other things better hill climbing.
Any of the Silvio or S30 or S40 that come up on the Marketplace part of the forum would be an excellent place to start. Sellers should be able to provide detailed pictures and specifications of which version, what components, additional equipment, modifications, etc. They are usually updated to indicate if they are sold or feel free to ask if they have been idle for a while.
Oh, I was thinking only of the higher end models because you mentioned S30. The older Sofrider (no longer made) and Q (Quest, QX100) models also had dual suspension, the new QX100 has only rear suspension. The newest QX100 is the current model with suspension - lots of rear suspension and ability to go up to 2" tires at both ends. My neck used to bother me from working at a computer desk all day and an old injury combined with riding my mountain and road bikes, but with the Cruz bike with 1.75" tires I do not get that strain until I have to switch to the mountain bike for winter snow and ice conditions.
Completely biased personal experience: I have ridden a conversion kit for the past several years which is completely non-suspended, very short wheelbase, with 1.75" mountain bike tires. It handles pavement, rail-trail, and reasonable gravel/mud roads well. Washboard gravel roads and very loose gravel I would probably want to switch to my regular mountain bike with front suspension if I was going to do lots of it. The difference is that if you can't see it and avoid it for large hits (couple inches or more) it might startle you or throw off balance. I postulate that this is exaggerated on my particular bike due to the steep steering angle, very short wheelbase (small frame), and extremely stiff non-suspended rear end (see my Avatar at left). I find that Cruzbikes recover balance very well because of the front wheel drive characteristics.
Wishing you all the best in your search. Welcome to the Cruzbike tribe,
Benphyr.