Michael probably meant MegaBIT per second (instead of MegaBYTE per second).
So a 396 Mb/s 4444HQ is 49,5 MB/s (1MB = 8Mb).
I work on PC and have no problem playing back DNxHD files with 175-350 Mb/s in Adobe Premiere with an average 2.5" USB3-HDD.
Though keep in mind what Michael wrote about 2 streams / writing + reading at a time (that's why I create low bitrate proxys when dealing with multicam Clips).
In addition to Guy's advice:
There are some Ai-S lenses on this list that I want to get soon, to.
But not to break the budget I use and love these ones (with a used metabones speedbooster and noname adapter without itnegrated lens):
50mm f.1.4 (even wide open if I want to have its dreamy kind of look)
50mm f.1.8 (very good wide open and perfect at 2.8; cheaper than the 1.4)
75-150 3.5 E (very affordable- makes me not miss longer primes at the moment)
Btw, I sold my panasonic 14mm 2.5 as well as the Leica 45mm 2.8 macro, and don't miss them at all (though they are very good).
Also consider that manual focusing with a follow focus does'nt work well with most native M/43 lenses because of the wired focus system.
On the other hand, focusing with the old Nikkors feels and works sooo fine :-)
My experience with GH1 / GH2 and Nikon Lenses:
First of all:
If you want to go the M4/3 + Manual Nikon (or almost anything else), your best purchase might be a (Metabones) speedbooster.
1. In combination with a "normal" Adapter (i use two 20€ pieces with no hassle), you actually double your lense arsenal (e.g. a 50mm with speedbooster turns into a 35mm).
2. you gain 1 extra stop, which means that you eather save money by not needing the very fastest lenses, or these ones become even faster :-)
3. with a crop factor of about 1.4 a Nikon 20mm could be wide enough for you.
My favourite lenses:
50mm 1.8 Ai-S (I have the 1.4 too, but the 1.8 is better wide open and perfect at 2.8)
35mm 2.8 Ai-S (with speedboster it's like a 50mm normal lense on full frame)
75-150mm 3.5 E-Series (bought it because I couldn't afford my desired 85 and 105mm lenses. It's very cheap, small, light, well built and great!)
I sometimes use the 14-42mm kit lense, too.
Here's a music video I made with these lenses / cameras (my first one, so don't blame the gear ;-) ):
Hope I could help a Little!