Superficially, it seems that a number of recent twin ditchings in the Channel were due to people running with low fuel to get the maximum benefit of cheap fuel.
But I don't think the IOM has cheap fuel. The Channel Islands certainly do have.
The last one to happen on its way to the Isle of Man was a Twin Comanche and it wasn't due to lack of fuel - the AAIB actually recovered the wreck and still found usable fuel in it despite it having sat at the bottom of the sea for three months. (I know the pilot, and she was coming from the Channel Islands - any time you do that you fill it to the gunnels because it's much cheaper there). The other notable one that springs to mind was a Baron that crashed not long after takeoff when the pilot lost control in IMC.
As for fuel I still fill it to the top it off at Ronaldsway before leaving rather than falling to the temptation of cheaper fuel elsewhere, because it gives me options should the weather turn sour.
Richard Collins in the 1970's operated a C172 IFR for several years to demonstrate the practicality and utility of SEP IFR. I think he gathered statistics on days lost to weather, etc, but in general for trips of up to 400~500 nm, especially with intermediate stops he was quite pleased with the outcome.
A modern 172 with improved crashworthiness seats, seat belts (with air bags?), glass cockpit and a FI Lycoming arguably may be a less risky proposition for IFR than a legacy piston twin.
A forced landing in a 172 is at 45 mph with reasonably good probability of emerging with only minor injury. Legacy twin piston accidents have a much higher probability of serious injury/fatality.
Not sure my risk appetite extends to SEP IFR at night, or VFR except for very good conditions.
I think one can do a lot more "low end IFR" in the USA, simply because they have so many more instrument runways, usually H24, avgas is everywhere, and there is no need for Customs.
In Europe, the avgas/customs matrix is sparse and a 172 has poor utility for European touring. Most of my European trips would have been much more effort in a 172, due to range alone, and I would have never bothered. Even one fuel stop is a major hassle.
Of course a 172 will be fine for short range stuff but I think there is little utility value in that in Europe unless you are working an unusual scenario e.g. flying between Bournemouth (where you live) and Bordeaux (where you work). Both have ILS, decent opening hours, and reasonable alternates. An easy 2hr flight and a horror by any other transport.
