I flew the Historic Helicopters Mk 5 a week or so ago - first time in a Wessex for 33 years and it felt perfect, even without the ASE (spares issue) - exactly the same as a Mk 2 except for some plumbing and electrical mods..
After flying Mk 2 in NI we had Mk5 converted to Mk 2 in Cyprus which retained the port side drop tank.
It remains the most stable helicopter in the hover I have flown - even ASE out!