SR
Are they NiCd: Yes
What makes them better: SR uses aerospace grade cells, not consumer cells. They also match the cells for each pack and actually test the cells.
GiantScale? Using two SR 2200 packs on RC, 9 servos on a 35% edge. I fly 5-8 10-15 minute flights on one charge and when I discharge the remainder of the pack I still have about 1/3 left. Number of flights I can put on a pack will depend upon how hard I flew. aggressive flight = more battery drain. SR packs don't last any longer than any other pack... a 1000 Mah pack is a 1000 Mah pack regardless of who made it or what chemistry it is. Performance is really not the issue... durability is. For example, SR packs are specifically designed for use in areas of high vibration, strain reliefs on the welds, etc.
Memory problems: What was the question again? Oh yeah, never had any problems witht he SR packs.
Why Use them when NiMH is lighter? A Sanyo 2200 NiMH cell weights 2.1 ounces. A SR NiCd 2200 cell weights 2.1 ounces? Yes, I just looked both of them up and I'm not making this up. How can that be? Maybe it is the NiMH people that have the superior marketing?
Cost Less? Consumer grade NiCd and NiMh are basically identical in cost. However, aerospace NiCd grade cells cost more, matched packs cost more to make and testing packs costs more than no testing.
What convinced me to buy these? I see it as a cheap one time cost insurance policy that I won't have a battery issue in my giant scale plane. Kinda like using two switches. Now, I've never had a switch go bad, but if it did, and I only have one, it is a guaranteed crash. So use two switches and use the best quality ones I can find. IMO Batteries are in that same critical equipment class.