I share the concerns about running into rattlers when hiking with my dog. I've heard and/or seen plenty of folks carrying their dogs out after they've been bit. It seems a really common area to get bit is on the face since they like to stick their noses into everything.
I mostly try to hike with my dog outside of prime snake season and/or at cooler, wetter times. If I'm brining him along on a hike when rattlers are a good possibility, he stays on his leash and when possible, stays behind me. He's super curious and has a strong chase instinct, so I fear he would try to pounce on a snake just to see what it is if given the chance. The few rattlers we've encountered with him so far have been sleeply, slow-moving and lazy and Bixby has just walked right by them without even noticing them, thankfully.
We've been considering, and probably ultimately will someday complete the rattlesnake avoidance training with our dog. The other thing we're considering is a rattlesnake vaccine available at the vets office. It doesn't make the dog immune to a bite, but it buys you quite a bit more time to get medical attention. Some good friends have had successful results with the vaccine on at least one occasion with one of their ranch dogs that has to contend with snakes not only at home in the Los Padres/SB foothills but also on regular horse-packing trips in the southern Sierras.
In our house, the dog is part of the family. He loves to go hiking and camping with us and we enjoy having him with us. I want to bring him along as much as I can and just have to take reasonable precautions to safely do so.