I have been buying 2100 NiMH 6V AA packs from Maxx Products for about $25. They weigh the same as your NiCads and the 1250, 1450 and 1650 NiMH. Here's there web page http://www.maxxprod.com/mpi/mpi-7b.html

You can quick charge between flights, but I get more than 5-6 flights on a pair of them in my 35% Extra, also use them in my other smaller planes, because they don't weigh much, last a long time and quick charge on my Sirius charger in nothing flat.

Hope this helps.