@CoParaTech - You may have already resolved this, but the problem you’re having with S3D printing that OSHW keychain is actually a problem with the STL mesh. I encountered the same issue.
That’s the model from the USB stick that came with the Lulzbot Mini, right? That model has some sort of self-intersecting face issue that gives the S3D slicer a problem. If you look at the print preview carefully in S3D, you’ll notice a bunch of “air” between layers 5 and 6 (assuming a .25mm layer height, 0.425mm first layer). The filament on layer 6 doesn’t have anything to stick to because layer 5 is so far away, hence the “stringing” you are getting. The root of that problem is a bad model.
By default, Cura has the “Fix horrible - Type A” logic enabled, which corrects that problem during slicing and the model then prints OK. If you turn that feature OFF in Cura, then this model will exhibit the same problem as it does in S3D.
Cura does seem a bit better at automatically “fixing” certain kinds of model problems than S3D (although S3D may be better at others). For this model, and it’s specific problem, you need to use S3D’s “Mesh, Separate Connected Surfaces” feature. That will split the intersecting faces into (2) models, put both in the current process, and (ta-da) the keychain will print perfectly!!! Give it a try.
Here’s what that model looks like for me, printed from S3D in HIPS – after using S3D’s “Mesh, Separate Connected Surfaces” feature. No strings! 
I’ve been working with S3D quite a bit. The biggest problem I had with S3D’s default Lulzbot Mini profile was that the “Autoconfigure Material” only remembers/tracks (4) parameters (Temp, BedTemp, ExtrusionMultiplier, FanSpeed), and the “Autoconfigure Quality” only remembers/tracks (6) parameters (LayerHeight, SolidTopLayers, SolidBottomLayers, SkirtLayers, SupportInfillPct). All the other parameters are “global”, meaning they don’t change when you change the Material or Quality dropdown choice.
I was able to fix that by editing an exported XML profile and then re-importing it. A lot of work, but it produced a pretty decent S3D profile for Lulzbot Mini that remembers (20) parameters for each Material choice (including different start/end scripts for each material, with appropriate clean/probe and removal temps taken from the Lulzbot Cura profiles), and (30) parameters for each Quality choice. It’s still a work in progress, but I’m getting pretty good results with it.
Here’s a link to the S3D FFF profile file. Right-click and “save target as…”, then import the file into S3D if you want to try it. There are Material Choices for ABS, HIPS, PETG, Ngen, Alloy910, Cheetah, and PLA (with Fast, Medium, Detail quality choices for each), plus T-Glase (with Clarity/Strength quality choices).
https://1drv.ms/u/s!Aj5_Sqpk1E8cvGxCK1m2Bjli1Oxq
And here’s a link to a spreadsheet that explains the profile design, including which settings are tied to “Material” choices and which are tied to “Quality” choices, along with the specific settings used. Of course you can change any of the settings – and as I said, this is a “work in progress” so some fine-tuning may be needed. Most of the existing settings were gleaned from the default Lulzbot Cura profiles, although I altered a few based on testing results, or simply because certain Cura settings don’t have a one-to-one relationship to an S3D setting.
https://1drv.ms/b/s!Aj5_Sqpk1E8cvG2cTNvm0d3VgDIY
Let me know if any of that that helps!