What do you consider heavy editing? Which software do you use?
I bought a Lenovo y580 a couple years back (approx $800) with an i7 3610qm and GTX660m and it edits well, but not as good as my old Q6600 w/ GTX 580. Rendering was identical on both machines.
Keep in mind that when editing, the video rarely slows things down (simple edits like cuts transitions etc...), but adding color corrections and effects do. In that case, you would need a pretty hefty GPU. Also a general rule of thumb:
Editing = GPU
Rendering/Encoding = CPU
$1500 budget for heavy editing is not enough for laptop
Your being off buying a desktop workstation
I purchase HP Z620 E5-2650 in Newegg and the supplier is AntOnline
It's cheaper for you to purchase it from AntOnline direct because Newegg charge taxes
See my spec on HP Z620
You can see the video in youtube website for my reviews
I use Pinnace Studio 16 Ultimate and Canon RF H42 mini camcorder