Scope devices are external HARDWARE devices, as far as the sequencer is concerned. they NEVER run on the cpu. the "wrapper" is only a connection between the sequencer and the synth or whatever. Scope IS the actual environement that the sequencer is running in(virtually), NOT the other way around. xtc mode is actually a simplification, a limitation of Scope. in return for a fixed routing(Scope mode offers freely dynamic routing), Scope plugins run inside the sequencer, with latency(compensated for on playback by the sequencer). in xtc mode, for all intents and purposes, Scope behaves like a normal, stupid windows soundcard.
Scope mode is true virtual reality that makes everything inside and outside the computer talk to eachother in what is(virtually) realtime. if you understand music production hardware, have a real studio, or wish to learn about real gear, then Scope mode is a way to have literally 100's of thousands of dollars of REAL gear in a compact package. it is not really dependant on the computer, except for the human graphic interface and the sequenecer/recorder. like all real gear, it never really becomes outdated, because real gear that sounds good ALWAYS sounds good. that's why old synths and compressors and mics are often super expensive, even though they're "obsolete". just like with a pile of gear in the real world(multitrack recorders, compressors, mixers, synths, delays, etc), there are infinite ways to connect the devices in Scope. every connection possible in the real world, can be made in REAL TIME in the computer with Scope. with Scope you can also go in and out of the real world as much as you like, with no more latency than with any other HARDWARE. you can also stream from one program to another as you please(i use Cubase for my multitrack recorder and stream to Samplitude for my two track deck). in this mode, i mix in the Scope mixer(but still use whatever vsts i wish as well as sequencer automation), the benefit being much better sound(imho). the other beautiful thing about Scope is that it plays well with all your future hardware. it's a 10-20 year investment, not a 6 month toy.
these two modes can't blend with each other. it's either one or the other. mix in the sequencer or mix in Scope, but the devices and presets are the same.