I think it's interesting that this article says that larger dogs are often preferred for search and rescue animals.
I can definitely see why that might be so, as people are usually lost in extreme conditions and are very rarely found quickly and easily, particularly once it gets to the point where a dog needs to be brought in.
But, I do think they might need to take advantage of what smaller dogs have to offer as well. Many of the smaller breeds were developed for the same reason that the larger breeds were developed, as hunting dogs. The smaller breeds were supposed to be able to go into a burrow after, say, a fox or a rabbit, and needed to be able to guide themselves in a small area with a keen sense of smell.
Now when we think of small breeds we think of useless yapping creatures that get carried around in handbags, but terriers were bred to handle all conditions and to be brave and fierce in bad conditions.
Granted, they couldn't keep going as long as the bigger dogs, but if their traits were bred with a bigger dog, or if they were kept in reserve for when the search had been narrowed to a particular spot, they could be very useful.