it is noteworthy to note that I am using a UAG case for the SP2017. This slows down heat dissipation and cause my device to run 1-2C higher than normal.
There are throttles when I do CPU heavy programs for extensive person of time. I will try and do some benchmarks so you have some quantitative values to work with. However, for web browsing and light-moderate CPU use, the SP2017 managed to keep the CPU cool and boosting fine.
Battery life is certainly the most noticeable boost. Bigger batt (45whr) + improved processor efficiency + no fans = 9 hours of studying with onenote + ppt + spotify on battery saving mode.
Speakers are a nice boost as well. A little louder and more punchy mids and highs.
SP2017 pen is great, input lag is less noticeable and it feels more natural. I am a biology student, drawing lines to annotate is important. The SP4 has some major jitters when I draw diagonal lines, however the SP2017 pen is much smoother and has significantly lesser jitters.
That being said, I am not an artist and although that 4096 levels of sensitivity is nice (as well as tilt support), the SP4 pen is more than serviceable for my use as a student.
If you do require CPU intensive work to be done and are on a budget, get the SP4 I7.