In straight and level constant speed flight you experience 1G, just as if you were standing on the ground not moving - all forces are in balance.
If you roll into and maintain a steady state turn while maintaining height you will experience an increase in steady state G - 1.4 G at 45 deg AoB and 2 G at 60 deg AoB because the you are accelerating towards the centre of the turn.
As Apolloheli pointed out, you can't fly IMC by feel because of the lack of the visual cues your brain needs to orientate itself and the fact that acceleration in all axes affects the vestibular organs of your inner ear causing powerful sensations of pitching, rolling or yawing.
Whilst it is possible to fly instruments without an AH/AI it takes practice and is far more likely to end in tears than when using an AH/AI.
In the thread accident, all we know is that what he wanted to do with the helicopter isn't what the helicopter was actually doing - typical symptoms of disorientation.
If you end up IMC when you weren't expecting to and don't lock straight into an instrument scan, things are going to go wrong quite quickly - if you have the aircraft trimmed straight and level and don't move the controls apart from raising the lever a little to initiate the climb then you might survive to VMC on top.
If you go into cloud already in a turn you are halfway to the crash if you don't lock onto instruments and if this happens while you are moving your head around looking for external references you have a bullet in the chamber and your finger on the trigger.
For those that haven't experienced it, I cannot explain how powerful the illusions of bank can be - the leans - and how easy it is to end up in a spiral descent. If you have the height and awareness to recognise the situation you can recover it with good instrument flying skills and I have had to take control from disorientated students in this configuration many times in cloud. If you don't have the height and awareness you are doomed.