Hi Jan,
The 100 mm is the 35 mm equv. of a 200 mm and will put greater distance between the port and subject. At life size (1:1) the subject will be the same size as it would be with the 35 macro at 1:1, the only difference would be distance to subject and shallower depth of field. The 100 mm macro will be a specialty lens for skittish subjects and NOT a standard macro choice, at least not for me. I will also take a higher degree of skill to use as DOF and steadying the lens will be challenging.
The Olympus standard range lenses have tested very well against the competition in the same price and angle of view range. The new standard wide zoom will not be weather sealed or as robust in build quality. However I use the 35 mm macro (under $200.00) all the time with outstanding results, you just can't get as close as you sometimes need to be because it focuses to about 3 mm from the port.
Phil Rudin