OK, MX-4 arrived today and doing some tests now.
On the dried up stock paste it thermal throttled from Wprime alone, so i cant really compare to it.
Temps monitored with throttlestop and afterburner - only reporting the max temp registered, not average.
Wprime 1024 + Heaven 4.0 (GPU OC'd)
Old Arctic Silver Ceramique:
CPU: 92C
GPU: 63C
so while this is a very unreasonable load i'll never encounter in normal use of the laptop, its worth noting that these temps got hot enough to almost throttle the CPU. on a hot summers day, it WOULD throttle.
Brand Spankin new MX-4:
CPU: 86C
GPU: 65C (FPS was slightly higher, i think heaven got more CPU power this time around)
So the MX4 was definitely a winne this time around, but the ASC had dried up and gone all stringy so it wasnt really a fair fight i guess.