I notice that the figures given for a 50 hour on a PA 28 are based on 8 man hours.
I would say that the work content between a helicopter and light fixed wing are similar. I believe that 5 man hours for a 50 on an R44 is cutting to the bone.
Most of the work scope on a LAMS (A) 50 is almost identical to a LAMS (H).
So if its 8 hours for a PA 28 then 8 for an R44 would not seem unreasonable. The only real difference being the hourly rate, but again thats a commercial issue.
The reason Avionics, Twins and Helicopters cost more is that the market will stand it.
If you fly single piston helicopters you need money.
If you fly single turbine helicopters you need loads of money.
If you fly twin turbine helicopters you need someone elses money.