I don't know about the waste being worse, since none of it will be transuranic. All short-lived activation of a few hundred years at most, you could just switch it off and mothball it really.
Totally agreed about the neutron embrittlement, I think that (IFMIF aside) this issue has just been brushed aside as a materials engineering 'detail' to be dealt with as part of commercialisation in a few decades when it might actually make the whole concept of using fusion for energy impractical.
I think my prof's main point was that the volume of waste could be problematic. If a fusion reactor had a 50-60 year life it could activate a lot of material. The volume of fission reactor waste is small enough to be stored on site (so far) for decades and reprocessing can reduce that dramatically.
Totally agreed about the neutron embrittlement, I think that (IFMIF aside) this issue has just been brushed aside as a materials engineering 'detail' to be dealt with as part of commercialisation in a few decades when it might actually make the whole concept of using fusion for energy impractical.