All the above proves is that a whole as yet undiscovered world can exist in some corner of aviation.
Indeed.
For a start, how often does a GPS "throw a wobbly"? What sort of a GPS are you using??? Was it made in the 1980s?
It probably was. The make is Trimble, I forget which model, something like a 1201.
IFR with no HSI (presumably meaning no slaved DI) in a helicopter??? What kind of masochistic exercise is this?
Most aircraft have a nice HSI, some have a slaved DI, RMI, OBS. We don't get to choose!
The biggest problem is that anybody who can fly a helicopter while holding a heading to an accuracy where the slide rule would deliver a more accurate solution than the simplest rule of thumb (e.g. max drift is half the crosswind, etc) is a robot.
It is perfectly feasible to fly our helicopters to a degree of heading. Wheel is more accurate than rules of thumbs, but we still use our thumbs as well.
This is simply unreal. Could be an RAF or ex RAF crew perhaps, which was never exposed to the outside world?
Wash your mouth out!

Never flown military. Ex GA.
Perhaps the most serious comment I can make is that some things can be practiced by very high hour highly trained pilots which would be completely stupid and inapplicable to all the rest.
There are many ways of skinning the aviation cat. None are wrong, some might be seen as inappropriate but at the end of the day everything from rules of thumbs, whiz wheels, GNS 430s to full FMS are valid. To critisise any one of them is folly.
Why not just fly partial panel, single pilot IFR, no autopilot, at night? Then you don't need much avionics, so even less to go wrong.
Its not about masochism (although it maybe sadistic tendencies among management) or machoism. It is about being able to keep the show running regardless of the level of kit fitted to the machine. There is a huge dumming down of aviation in professional levels due to more advanced hardware. I prefer to fly rather than push buttons.