Hollo
I take your point but then the faster the aircraft the less likely you are to survive a ditching.
In your microlight into wind your forward motion will be at snails pace.
we have all seen a car crash into a brick wall at 30 mph, hitting 20 foot block of moving water would be similar.
Ok if you limit your crossing to nice high pressure no wind days with a flat calm sea your chances of survival are probably high in slower and faster aircraft but in my experience pilots cross in SEPs when its windy and white caps cover the sea
On those days which around the UK probably account for 70% of sea conditions you are better off in something with a slow stall speed which will plonk down into the ocean rather than ploughing into it, so your better off in the microlight
Statistics are great but not so great if its an unlucky day and the failures or partial failures in pistons I have experienced means I don't fully trust them.
Too many moving parts
But its risk and sometimes you just have to bite the bullet and go
Pace