Mark, I'm flying the Perspective + system now, which is Cirrus version of G1000 nxi (I'm sure you know this but for others who may not). There are so many ways to do this we are getting tripped up in it in this discussion. I always load the full approach to the IAF that makes the most sense for where I am, I almost never load VTF unless I absolutely know I'm being vectored, like when flying from a missed procedure and the controller tells me to expect vectors.
Around here 95% of the approaches are VTF by ATC, but that 5%, which can be a surprise, are the ones that can trip you up, so I wait to hit the VTF button until I am sure. That said, getting the approach reloaded is just a few button pushes, no big deal if you're proficient at it.
Activating VTF after the full approach is loaded is pretty easy in the Perspective system. Hit PROC, a couple clicks on the knob, and a button push and you are done. Where as activating a leg is generally more pushes and more thought, but you've already pointed out the other reason VTF can be better, that's when you are vectored beyond the last fix on the final approach course.
Just don't forget to push VTF or to activate a leg, otherwise things get interesting when close in and you realize you are not going to intercept the final. Hand flying it is.
Finally, I'm pretty new at this, so I'm parroting what I've been taught, with a little but growing mix of what I've learned so far thrown in.