Looping - probably not a big issue - the 135 has a big hinge offset - watch the mast moment as you fly around and do manoeuvres - nothing much happens compared to the loads you can get on the ground unless you pay attention.
Rolling - Think about the resultant forces - the BO105 suffers in the tail rotor and subsequently i would have my concerns with the EC135 in the area of the ring frame.
Get back to us. I'll put the popcorn on.