According to common sense I've never seen a NIMH and NICD both with 2000mah, NICD is always lower.
Your source of information is extremely unreliable, this is the same store that believes a systema M100 is a 260-300fps spring lol
I know they make a 9.6v 1700mah NICD nunchuck, but their 2000mah battery is a large.
http://www.wgcshop.com/pcart/shopper...6V%20Batteries
http://www.wgcshop.com/pcart/shopper...6V%20Batteries
http://www.wgcshop.com/pcart/shopper...6V%20Batteries
Either way NIMH is your best bet.