Semi,
My feeling from your comments is you may not be familiar with the EC135.
As the aircraft stands at the moment the 50 hour and 100 hour are "checks" not periodic inspections.
The 50 hour includes 2 items: Check the tapes on the blade cuff covers and check the friction pads of the rotor brake. Most people run without the blade cuff covers now so that is more likely only one item.
The 100 hour adds 2 more items: Check the skid shoes and check the blade cuff vent holes.
The "periodic" inspection at the moment stands at 800 hours or 12 months with an intermediate inspection at 400 hours.
I fail to see how the 50 and 100 checks would detect any major defects involved with an increase in MAUW.
The "checks" can be carried out by a pilot depending on how your specific authority views it.
If you have PW engines (not familiar with TM's) the periodic inspection is 800 and 12 months with the only oil change requirement being calendar time.
Technically speaking a release to service could be issued for 800 hours or 12 months as this is the periodic inspection interval.
Servicing includes -
Change HYD fluid 800/12
Grease S/Plate 400/12
MGB Oil 600/12
TRGB Mineral Oil used 400/12
TRGB Synthetic Oil used 1200/36
Rotor Brake Fluid 800/12
There are of course supplementary inspections which are not specific to the whole fleet and depend on the mod status of the aircraft.
We operate a P2 and I do have factory training on the 135 in Germany and also the Pratt engine.
The aircraft here in .de are operated and mainained in this way and it seems to work.
It would not surprise me if the BGS and some other operators are already operating at these limits.
I'm afraid I don't share your concerns.