I’ve had a teammate who was AFAB, NB and went on testosterone. I also totally get the feeling of wanting to be inclusive, but of also having picked a WFTDA league over MRDA because of the gender thing (I’ll be curious to see if the WFTDA open division takes off - because hey, not gonna lie, I don’t feel comfortable playing a full contact sport with male-coded bodies against people I don’t know, because of some bad experiences with men before, and I’m torn between wanting roller derby to be a great welcoming space and I’m trying not to be transphobic or TERFy, but I also worry about potentially losing the empowerment I feel here - and I think a lot of people probably have those same feelings but it doesn’t get talked about because of the reasons you mentioned).

honestly - I didn’t notice a real difference with the hormones - the teammate certainly muscled up a bit, but so did someone else who started lifting weights. They didn’t suddenly become an off the wall dudebro going for wildly dangerous hits or anything. I’ve played against trans women and same thing - I didn’t notice anything that different compared to other teams I’ve played.