I have switched all of my planes to 1650 AA Nickel metal's. They are the best bang for the buck for me. I have them in all my planes, I buy them from Dave Thacker at Radical R/C........ Dave's got the best prices and outstanding service, A+. Hes top shelf to deal with and I get them in two days. They are as reliable as any nicad I have ever used in 25 years of flying........

103/17 

I use mostly NiMh packs for my planes.  For my bigger stuff I use two 5 cell 6v 2000 mah packs. No fancy distribution stuff , just in a spare channel with it's own switch.  Not that there's anything wrong with the big regulator and battery sharing devices, it's just that it turns into another single point of failure. 

For the smaller stuff, which is the bulk of my squadron in the hangar, I use 4.8v NiMh packs ranging from 1650 mah to 2700 mah.  I love that I can just put them on peak charge if I decide to go fly at the last minute without worrying about NiCd memory issues. Since I'm already running on nominal voltage, no regulator is needed and I enjoy many flights without the need to recharge.

I have also been moving to NiMh for my transmitters as well.  With the longer charge capacity of the receiver packs, I figured I better have the radio last as long so I don't need to field charge, though with these packs it's no big deal.  I just plug them in and hit Peak Charge and watch some flying from a nice comfy seat knowing my next flight will be in just a few minutes.

Lawrence - I put a 2700 MAh NiMH in my Futaba Super 8 and have not regretted it a bit!  Charges seem to last forever.

I would caution you to be careful on the peak charge tho - I understand that if the NiMH cells get too hot then you have shortened their life considerably - no more than 10 degrees F over ambient temperature.  And you should charge the NiMH at 1C or less, to preserve longevity.

 Buy a sirius charge pro and forget about everything you know about charging. They fast charge NiMH batteries all day long and never get hot or overcharge. The microprocessor takes care of it for you. No switches, no calibrations, no polarity issues............they do it all. Check with Dave Thacker at Radical RC hes the one who fixed me up when I switched to 1650 packs in everything I own. These chargers will even fix memory issues with Nicads. I cant say enough good about them. Guys at our field are switching over from whatever they have to the Sirius stuff. Its expensive but its miles ahead of anything else I have used or seen. I dont even charge at home anymore. I only charge at the field.

103/17

Agreed re: the issue with careful charging, however, I have a flying buddy who bought a Sirius right from the guy at the AMA show.  He was quite sold on the gentlman's claim that their chargers are incapable of creating a memory in NiCd cells.  Well, so far he has brought me 2 packs that would not get a good charge from his Sirius.  I cycled them on my Hobbico Accu Cycle Elite and was able to bring them back to over 95% capacity. One was NiCd and the other was NiMh. 

IMHO for the money he spent on the Sirius charger that is very easy to use, but does not provide any information to the user other than red and green LEDs, he could have spent literally $10 more to get what I feel is a much better charger.  I can't attest to the claim of the Sirius charger's ability to "fix" or prevent memory issues in NiCd batteries one way or the other, but I know for sure what the performance of my charger is capable of. When I do cycle my NiMhs occasionaly to test performance, it tells me exactly what the battery's capacity and voltage is so I know it's still performing at it's peak.  I have a 1650 NiMh pack with over 150 days of flying on it and it consistently rates at over 100% capacity when I cycle test it.