Once your engine fails the airplane is the property of the insurance company, your only goal at that point should be to survive.
Using a whole-airframe chute increases your chances of survival whether over land or sea.
The things that kill people in forced landings of any kind are high-g deceleration and post crash fire.
A parachute decreases the chances of both as you have very low lateral speed and much less chance of fuel tank leaks.
A parachute also will increase the chance the airplane will remain upright, so escaping the aircraft will be much easier - very important in a water landing!
The only reason for a "normal" ditching procedure is that you have no other choice, using a parachute if you have one will almost always be the right option.
The only time I would consider otherwise is if I had enough altitude to glide to a safer emergency landing spot.
If pulling the chute would mean landing in water or dangerous terrain but gliding would mean reaching land where a forced landing was reasonable
I'd probably opt for gliding.
aviation.stackexchange.com/users/1791/GdD
First, according to one operating handbook for the Cirrus SR-22 (there are several versions out there), pulling the chute is the correct ditching procedure (CAPS is the parachute system): Ditching Radio ............................................
Transmit (121.5 MHz)
MAYDAY giving location and intentions Transponder........................................................... SQUAWK 7700 CAPS ............................................................................. ACTIVATE Airplane.........................................................................
EVACUATE Flotation Devices ............
INFLATE WHEN CLEAR OF AIRPLANE Second, the conditions were
reported to be windy with high waves:
Weather conditions at the time of the rescue were seas of 9 to 12 feet and winds of 25 to 28 mph.
Those would be tough conditions for ditching in.
I've read several times that when light aircraft ditch, the pilot and passengers usually survive the impact but they often struggle to exit the aircraft successfully.
This article and video explain in detail how difficult it can be to exit an aircraft in the water, even in good conditions.
If the aircraft flips or cartwheels then exiting would be extremely tough and the rough sea would make it much worse.
Since the parachute lowers the aircraft straight down in a more or less level attitude, the chance of flipping over is greatly reduced.
The downside is that you no longer have control of where you touch down relative to the waves, so you might land just in front of one but that still seems like a good option compared to the risk of flipping the aircraft on impact.
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Maybe pulling the chute is the normal ditching procedure for a cirrus with an airframe chute.
The splash down looks to be very gentle compared to a normal gliding ditch with fixed gear.
It's also less prone to pilot error; once you are dangling there is not much the pilot can mess up.
I imagine the checklist being something like: pull chute when aircraft stabilizes open door put on life vest and prepare raft should plane roll and sink get out and on the raft
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The odds of survival with the chute are currently at 100% (Per Cirrus) and the odds of surviving a ditching are much less.
The plane was lost in the Pacific either way.
The correct thing to do is pull the lever and ride it down, live to be a great pilot another day.
The real question is what did the pilot do wrong to end up in that situation?
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The proper response to losing the engine would be to follow the emergency procedures checklist.
In that you will find it says to deploy the ballistic parachute.
While a better option, the ballistic parachute has its own drawbacks.
I recall when getting checked out in a Cirrus years ago by an approved training provider that I was told the impact with chute deployed can be up to 8 G's.
So I would say not 100% survivable.
Actually I know of a Cirrus that went down near Sanford Florida a few years back that deployed the chute and the occupants died.
aviation.stackexchange.com/users/7188/Brian
In  this incident near Hawaii , a Cirrus SR22 had fuel problems and deployed its  airframe parachute .  My question is why did the pilot deploy the parachute rather than perform a "normal" ditching procedure in the ocean?  For reference, here's  the video .
Why did this Cirrus deploy the parachute while ditching over Pacific Ocean?
aviation.stackexchange.com
<emergency><ditching><airframe-parachute>
aviation.stackexchange.com/questions/12048
aviation.stackexchange.com/users/700/Keegan
When the engine fails on a light aircraft the correct thing to do is use the parachute. This gives the pilot a greater chance of survival and als helps to prevent the plane from flipping over. Apparently, many people survive the impact of a light airplane crash but have difficulty getting out of the aircraft when it lands on water. When light aircraft ditch, the pilot and passengers often struggle to exit the aircraft. A parachute makes it more likely that the aircraft will remain upright rather than flipping over. This makes it much easier to exit the aircraft. The objective in this situation is survival. Using a whole-airframe chute increases the chance of survival compared to ditching. A ditching procedure would only be used if there is no other option. Using a parachute will normally be the right choice and will increase the odds of survival. 
The objective in this situation is survival. Using a whole-airframe chute increases the chance of survival compared to ditching.  A parachute also makes it more likely that the aircraft will remain upright rather than flipping over. This makes it much easier to exit the aircraft. When light aircraft ditch, the pilot and passengers often struggle to exit the aircraft. Escaping the aircraft is much easier with a parachute landing. A ditching procedure would only be used if there is no other option. Using a parachute will normally be the right choice and will increase the odds of survival. 