You need to be aware of your subdivision level when you export. ....You need to apply the smooth modifier in DAZ and go to subdivision level 1.
Just for clarity the smoothing modifier does smooth the geometry a bit, but serves as a way to prevent pokethrough when attached to the host figure. In all honestly a model you create yourself shouldn't depend on this too heavily and should look smooth without it.
If you use the hexagon bridge daz automatically sets the model to base resolution before sending it over. If you are exporting yourself then yes, you need to set the figure to base resolution if you have applied sub-d in daz otherwise you are going to quadruple the poly count.
Depending on the density of the mesh sub-d shouldn't even be needed. Based on the geometry I see in the screenshots I wonder if something else is at play.
I've noticed that it has a tendency to try to eat RAM for a while, then eventually settles down
Since Hexagon is bad with textures anyway, I work in wireframe mode and it utilizes far less ram this way. Once you display textures, the ram utilization will shoot up and eventually you will hit the 3gb limit. But yeah that 64bit fix is the first thing I install after I install hexagon.
Its myriad issues are likely why zBrush was embraced by many users and vendors, though a lot of them do still swear by Hexagon. Personal preference, I suppose.
Yeah Hexagon is a modeler and Zbrush is a sculpting tool so they work very differently. A lot of people who work in zbrush start elsewhere(to model) and send it to zbrush for detailing. But there are people who do all their work in Zbrush too.