I'm not going to get into the debate about whether it's better to be sitting on top of an overturned multihull or inside a rubber raft.  It's entirely a matter of subjective risk assessment.  The minivan has been replaced by the SUV as the suburban vehicle of choice for hauling the kids around, despite the fact that it's much more likely to flip over.  Why?  Because it makes people feel safe despite clear and plentiful evidence to the contrary.  In the sailing world, the evidence is far less abundant or decisive.  What little evidence there is shows that non-racing multihulls flip about as often as non-racing monohulls sink (which is almost never), while racing multihulls flip about as often as racing monohulls sink or otherwise suffer so much damage that they have to be abandoned.  Neither seems to me to be "better," you just pick which possibility you prefer. 

Boat U.S. released  "Why Sailing Boats Sink and 5 Tips to Prevent Yours" and reports this:

Sinking at the Dock:

Below waterline fitting 44%
Stuffing box leak 33%
Keel and centerboard 7%
Rain 7%
Head back-siphoning 3%
Above waterline fitting 3%
City Water hookup 3%

Sinking Underway:

Struck submerged object 40%
Prop shaft or strut 16%
Below waterline fitting 16%
Grounding 8%
Stuffing box leak 8%
Storm/knockdowns 8%
Above waterline fitting 4%

It's good to know that none of the items in the first list is applicable to multihulls and most of the second list isn't either since the boat has positive bouyancy.  I've already stuck a rock hard enough to rip a chunk out of the daggerboard with no effect on the hull, and I don't have an inboard, so that covers over half the possibilities.

I suppose Mureadritta's owners should take solace in the fact that their tragedy was the most common cause of sinking.

Mureadritta's XL versus the whale

I later found out that the designer of this boat believed that it wouldn't have sunk at all, despite being holed, because like a multihull it was foam-cored.  Imagine how high it would have floated without all that lead attached!

Even a Corsair that was smashed to pieces on the rocks of the Farallones ended up on the beach 300 miles away a few weeks later, looking like a dead crab.  Sure wouldn't have been a pleasant journey, but it beats drowning or floating in a rubber raft.

tri on beach
The tide is slowly turning in favor of multihulls.  Around the 1960s, fiberglass wasn't considered a suitable building material for an offshore yacht.  Just a few decades ago, serious cruisers wouldn't consider leaving port without a full keel to protect the rudder.  I predict the monohull bias will be considered just as quaint as these precautions in a few more years.