Well I think the question becomes, what sort of situations are actually happening, and then what capability is needed to mitigate those situations? If an area's data says that there are enough people whose position we know, but because they didn't get rapid, low level stabalizing triage care they ended up dying then a system like this might make sense. But if most of the cases involve searching, higher level care, an eventual medevac anyways, or any combination of the above, a SAR organization is probably going to need a helicopter anyways. If you already have a helicopter with hoist capability, then it will probably be hard to make the math justify the additional expense.

While having a smaller fleet of helicopters induces a smaller number of critical failures, if the advantage is the amount of time it takes to get to a location, you'd need a lot of jetpacks to be spread out enough to beat a helicopter. With an advertised endurance of 5-10 minutes, this won't do more than get you a small hop to a remote location. The searching and most of the traversing is going to have to be done by some other vehicle. If every 4x4,truck or ground search party needs to have one of these (and be trained to operate it proficiently), I have a hard time believing that you aren't going to be quickly running an operation that's more expensive then a helo operation. That being said, maybe some areas could use this. Perhaps a place with canyons or cravasses, where people could fall down but rescuers could still mostly move rapidly using ground vehicles.

As far as the downwash, while it is a concern it's also something that can be managed. The heavier the aircraft (more equipment, endurance, and reliability) , the more downwash. This jetpack has a small down wash footprint (but I bet it's still really high under the jets since it's a pure thrust aircraft) but the tradeoff is in endurance and equipment.

But again, there might be some areas that could benefit from it, but I think it's a solution looking for a problem. Other than the gee wiz factor, I doubt any of the SAR agencies in the US would set up a system like this.