I agree with the economy stuff, it felt like I could just sit in one place and get a decent income by spamming scavenge and living off disposable biocells (not bothering with carcasses/biotanks at all)... but upgrading the salvager/harvester would take forever to pay off with the low rate of energy to power to resource conversion. I think that payoff was something like 8 minutes per level, and you had to stay put by the node, and you had to pay power for it.
I interestingly had a bit of a different experience. I found that using spinners with repeaters worked really well extremely early, and that very naturally flowed into using Bio, disposables at first but then getting some cells upgraded let me move that to being more passive energy while I worked on salvaging and other things since I just had to refill them now and then. Eventually I've gotten to where I am now which I consider 'end game' for the demo, where I have a lot of scavengers highly leveled pumping out metal and a fuser pumping out rare metal with energy cells powering it all in the positives, everything on updaters so its all just getting more powerful passively. I still have a bio engine, but its mostly to just burns what I harvest from POI's, since harvesting creates items I can sell, using what I sell to buy whatever resources the NPC's have to speed things up. I think my experience really covered the whole game in one flow. I feel like going straight to bio would have been painfully slow since you have to salvage and then swap out the containers constantly, which defeats the point of an idle incremental like this.