[Lou]

Wow, long one Hobby…..I’ll add my thoughts

The problem with using data based on comparitive accident rates is that the groups you are comparing are not equivalent in all other ways.  Amongst “recreational” divers who dive the buddy system you have a range from complete novices, to very experienced divers.  The may dive once a year, or several times a week.  Their kits may be configured with some self-sufficiency in mind, or they may not.  
The more technical divers are, on the whole, drawn from divers who already have experience and therefore the experience profile of the group is likely to be higher.  However, the dives they do are also likely to be more difficult.  Cave divers fall across a completely different range from cavers who dive, to divers who cave, and the risks and skills are quite specific and hence they train to cope with these special circumstances.
To try and use statistic to back one way or the other is a huge challenge when faced with no base-line other than these groups all breath underwater!
What feels right to me though is that ultimately you have to be able to rely on yourself.  Whether this means limiting your diving to that which you can surface from safely in an OOA or carrying redundancy, and varying that by depth & bottom time, depends on the individual and their personal ambitions and reasons for diving.  It is a slightly different argument to buddy diving.  
I believe a buddy goes much, much further than someone to carry an octopus.  A buddy is there for you when you feel uncomfortable, narked, or plain scared.  They can cut you out of entanglements that you may struggle with.  They can see problems begin to occur before you have any idea (bubble checks etc).  A buddy is anpother pair of eyes on a dive to spot trouble, or things of interest.  They are your sanity check.  Most of all they are your best friend in those moments under water and over those pints above it.  Really they are another, valuable and equally important, way of mitigating the risk.  You can do a lot of things yourself, but there are few of those that two of you couldn’t do better.