agree, I saw it too, in aqua forest aquarium, there is a tank full of amano shrimps and a couple SAEs, good size SAEs..at aqua forest aquarium in San Francisco i see SAE's cleaning their tanks very well. they were also left in a tank with lots of moss.
any fish besides catfish will eat shrimp. its best to keep shrimp in a tank w/o fish. the reason why you still have a decent amount of young shrimp is probably because those are the ones that could get away from the SAEs. half of your newborn shrimp are probably eaten. in my RCS tank every hatching has about 30 babies.
they have some nice show tanks and actually the plants you buy from them are the ones they harverst from their in store plant tanks. (The anubias barteri in AFA is about 12.99 a piece, may be too slow to grow in their tank and they charge more. )
about the SAEs, I came cross an article not long ago but couldn't find it anymore. says even with the same appearance there are two close related but different species, I am not talking about CAE, False SAE, or flying fox here, since a SAE can be distinguished by one pair of Barbels from others(two pairs). SAEs with one pair of barbels actually are two species, same appearance.
if it is true, I think the difference between these two SAEs are like the two types of killer whales, can not tell by their appearance but by what they eat.