this is all very interesting because if you go to the thread called 'Helicopter down in Yarra River........' they are suggesting wearing both a flightsiut and helmet whilst flying any aircraft, training or not!
You'll get all sorts of advice on this forum and it's up to you to decide which to take. There are different scenarios and different contexts and some advice is not suitable to be moulded into a "one size fits all" situation.
If you'd feel more comfortable in a Nomex flying suit whilst you're learning to hover, then that's fine - I'm just warning you of the reaction you'll get!
Cheers
Whirls