I am one of the fortunate few that have a whole group of hiking buddies that are similar to me (physically, mentally, age, etc). We have a good time when we all go hiking together and we have all become very aware of how far to push each other (physically and mentally). In my case I feel safer when we all hike together because we are all competent hikers and know full well the risk we all take by being in remote locations.

With that said there have been a few times when an outsider has joined us and does not fit in well. In those cases the outsider has definitely had the potential to put us all at risk. Fortunately nothing too bad has never happened in either case.

So I think it is a toss up. If you can find competent people to hike with that you are comfortable around I think you can be safer. But an incompetent person (hiking/wilderness wise) can put you at a greater risk than going it alone.

Just to add to that, it is also good to have a set of "what if" rules defined when hiking with other people. Answers to questions like...

* Should we get separated, what do we do, where do we meet?
* What to do in the case of a snake bite/broken leg/severe illness/etc?
* Who to contact for help?

Things like that. Of course I ALWAYS leave a complete itinerary with multiple people before going on a trip, solo or in a group.