ok guys......please take note
1) The consistency of a 8 AAs is not very accurate. As long as one of the batteries goes weak, you will have trouble using the grip as the power will go off. I have tried with all new fresh Akaline Batteries and also the Ni-Mh batteries. Problem.
2) Problem no.2 is 8 AA is heavier than one EN-EL4a
3) 8AAs will last you about 900-1000 shots......EN-EL4a will last 1900-2500 (depending how you use it)
4) Charging time is about the same but since EN-EL4a has internal memory circuit (to tell you when you recondition the batteries and when the 4 cycles life is up)
Taken from an article....
http://www.pdngearguide.com/gearguide/content_display/news/e3iba088905bb5e40482c1e282b67590dbd
The new Nikon D700
Nikon Unveils D700 digital SLR -- a D3 on a Diet (UPDATED: New Battery Info)
July 1, 2008
Dan Havlik
If you liked the image quality and spectacular low-noise/low-light shooting ability of the Nikon D3 but wanted something smaller and less expensive, you're going to find the new Nikon D700 ($2,999) very interesting. With the same 12.1-megapixel full-frame FX CMOS sensor as the D3 but with a camera body that's 20 percent smaller and lighter than that digital SLR, the much buzzed about D700 is stripped down in size but is designed with the same pro-level performance.
Even better for pros on a tight budget yes, that means most pros these days the D700 is $2,000 less than the D3. Despite the lower price, the D700 is not a lot different from the D3 in its feature set. Like the D3, it boasts a 200-6400 ISO range with "High" settings that let you shoot in the dark at up to 25,600 ISO.
The D700 has the same Scene Recognition system; the same 51-point Autofocus system with 3D tracking; the same Live View in two modes; same 14-bit A/D converter; same 16-bit image processing; same 3-inch LCD etc. etc.
On the downside, the D700's battery life -- 1000 shots on a single charge, according to CIPA -- is not nearly as long as the D3 which can capture approximately 4300 shots. Add on a MB-D10 Multi-Power battery grip ($249) and the D700's battery life jumps to 1900 shots, but only when you pair it with on EN-EL4a lithium ion battery (which costs extra.) The grip will also give the D700 8 frames per second shooting speed. (The other big difference between the two cameras is the D3 uses dual CompactFlash card slots while the D700 only has one slot.)
Below is a breakdown -- provided by Nikon -- of the battery life of the D700 in various configurations versus the D3.
D700 with one EN-EL3e 1000 shots CIPA / 2500 shots Nikon.
D700 with MB-D10 + one EN-EL3e approx. 1000 shots CIPA / 2500 shots Nikon Measurement Standard.
D700 with MB-D10 + one EN-EL4a approx. 1900 shots CIPA / 4300 shots Nikon Measurement Standard.
D700 with MB-D10 + eight AA batteries approx. 700 shots CIPA / 1000 shots Nikon Measurement Standard.
CIPA standard for EN-EL4a for D3 is 4300 shots (Nikon Measurement Standard is 4700 shots)
I would only recommend to use 8AA batteries IF your EN-EL4a batteries and EN-EL3e batteries are totally DEAD.....