well, I swear it took me much more than 3 days to get along with a digital mixer (outboard) once... and I knew SFP in and out already that time ...
what you try with Cubase is at least as complex, so you might adjust your schedule regarding expectations just a little bit
there is a special forum section about XTC mode, it's admittedly not the most appreciated part of SFP as it cuts off a lot of flexibility and it's more complex to set up - yet it's said (by those who prefer this mode) that it's not a fundamental problem to set up an effective environment.
as you're relatively new to the system it may be easier to first get familiar with what's SFP specific and then decide which mode offers the most convenient workflow.
the biggest difference is probably the realtime handling and latency compensation of VSTi plugins.
A lot of folks here consider the Scope mixer (and summing), synths and FX superior to native processing.
You should compare yourself (as it's also a matter of taste), but regarding my own humble opinion it took as long as to the release of NI's FM8 that I could say:
'now there's a VST synth on par with what I'm used from Scope...'
it may be easier to first focus on the latency free operation of SFP, monitor through the Scope mixer and record the direct outs via Asio in the Sequencer, in particular if you play guitar and possibly other instruments in realtime.
The Scope stock plugins are used by Fairchild in a 5 figure euro (my guess) console
'because they sound so good' (according to their website).
Don't underestimate that stuff - it's a different league than Steinberg.
These things may look a bit humble and unspectacular, but well, you wanted to make music and not brag about the most crazy fx processor (which is included in your Scope anyway, just at a different location ...)
I actually never had a problem with the Asio latency when I routed stuff to a VST host and even back - and I have the old Pusar which has 13ms per path...
For me it doesn't matter (for example on a long reverb tail or a granular FX) if that is 10 or 30 ms 'late', as I'd record
exactly what I monitor - all things come together in the Scope mixer.
btw as a guitarist you
must have Echo by SpaceF, if you ever use a delay
cheers, Tom
(just to add to the perspective)