Hi mikel54, I've now tried this in Ableton live with a similar track count and effects on channels on the Quantum. It can easily support two tracks of Kontakt with the Abbey Road drums (and some other Kontakt VST instruments!), 16 audio tracks all with Slate plugins, a reverb send and some FX on the master all stable at 64 device block size it sits about 30% on the Ableton performance meter and similarly in Windows task manager all is stable! Ableton has no dropout protection and all tracks are running at a low latency setting so I'd expect Studio one to be able to manage a fair bit better.
Unfortunately the performance is dreadful in Studio One in comparison. As my machine is capable of low latency playback of VSTs in Ableton even chunky ones like Kontakt it looks like the implementation of dropout protection and low latency with VST instruments and effects in a project is just very poor in Studio One. I tried removing Kontakt by transforming it to an audio track leaving the session with just audio files and no VST instruments (keeping VST plug in effects on the tracks) and it seems to handle the performance a lot better and I can get down to 32 for device block size and 4ms latency, but the Quantum has been unstable and cuts out during tracking and even at 64 it's not always stable. VST effects take a big toll on performance though for selected channels and it's struggling to record with any level of FX on all 8 inputs at one time. Basically at 128 buffer giving 8ms latency it's just about possible to record 8 channels of audio with minimal Slate plugins on each channel although that's full round trip if the values reported are to be believed.
In summary Studio One kinda sucks at running VSTs despite the newly added dropout protection and low latency feature workarounds. Under the hood from what I can see Ableton is massively more efficient at running VSTs so can run more tracks without any tricks to get the most out of it's audio engine. I've raised a support ticket so hopefully Presonus can advise on whether there's some magic settings in Studio One, Windows 10 or my BIOS which will dramatically improve things, I'll let you know if I hear back, I think the solution though is to save up for a shiny new 10 core Intel PC! ;)