Re the relatively-quiet Merlin, an ex-boss of a Puma Sqn who made Gp Capt while still in post once told us that in his time in Whitehall the subject of a new buy of Chinooks came up. After reading an MoD comparison of the merits of more Chinooks vs Wastelands (sorry, tuc, but after time on Lynx it's an opinion I hold strongly) Merlins the Minister was minded to go for the UK aircraft "as it was the quietest of the 2 contenders". Fortunately he was persuaded otherwise.
I never heard that claim from MoD about the requirement of the NI pax to discuss business en-route: farcical.