Thundercloud, this is a very complex topic, as am sure you are aware:)
I think that, in order to make a comprehensive, or even FAIRLY comprehensive, claim(which I appreciate you are only positing as a POSSIBILITY:)) that women composers excelled more in smaller forms, one would need to have listened to many, many women composers who wrote in such forms(symphonies, concerti, opera etc). There are two dictionaries available of (solely) women composers which will list works, and, possibly, recordings of such works. But I think to go on a few examples is not the best.... No offence.

Also, there is the sexist element here at work(not in yourself, Thunderbird; please don't misunderstand me!)but in hegemonic musical western history, which is mainly male-dominated; and where some women composers were railroaded into domesticity by their (male) partners, as was the dominant culture of the age; so opportunities for career development(in, for example, orchestral forms) were more limited. I am not an expert in this field; but there ARE experts(probably mainly women!); but I think we should avoid sweeping generalisations based on one or two examples until full research is done, by us, as individuals. It is a chicken or egg situation: WERE women more at home in smaller(chamber, songs) forms or did they not have the career opportunity, because of institutionalised sexism,to develop/get tuition in these forms.
As i said, its a complex, fraught subject... and i do not feel qualified to dsicuss it further other than raising these questions. I also note that there are few women members on this forum, which isnt just THIS forum(Mark and Alan)

, it is true of MOST classical music discussion forums.......
Like the sexual orientation question(ie. whether it is discernible in non-vocal music, where, even as a gay man, I would say music is ABOVE/TRANSCENDS this issue,) people will have strong opinions. So can we keep it, as we usually do, nice-natured?
Thanks
Steve