D500 vs D700

So I'm about to pull the plug and go ahead and order my nMP. My system will be hex core, 12 gig RAM (upgraded with crucial when it arrives), 1TB hdd, but I can't decide on video card. I really don't want to spend the $500+ extra on the D700's if I'll never notice much difference. Some are saying there is no difference between D300 and D500, but I believe the extra RAM and bus bandwidth will eventually be utilized by software, so I'd like to not go with the base offering here.

My uses are mainly low-end (read:small-time) video editing in 1080p (maybe some 4k stuff later in the year) for high school purposes. I also use Aperture (I currently have about 20K or more pictures in my library) with my D3000 Nikon. This machine will be replacing a 2011 iMac 2.5 i5, so I know it's an upgrade. Anything I order should be faster, and beefier.

I also know that if I can buy the D700's later, and if I decide I need them, then at that point it will likely be in the thousands to upgrade (in which case I'd just buy a new nMP).

So, if I'm not driving 4k monitors (2 to 3 monitors, 1440p at most), and if I'm not editing much 4k video, and my edits/renders are of videos 1 hour or less in length......shouldn't I just save the $540 (educational upgrade price) and use that for RAM/peripherals, etc?

Or should I bite the bullet, spend the extra $540 and never wonder?
UGH, I hate money decisions.