I considered Literary Discussions for a while on your suggestion, but since I will neither be refering to written works nor to the subject of writing about bdsm, On Topic seems the better choice.
My wish not to write on an external site is based on the following: my intended readers are all HERE. At Elliquiy. Wonderful people who I talk with about bdsm in various ways, roleplay and sometimes IM with, and others I don't know yet or simply am on pleasant terms with. And I don't write just to talk, but very much in order to get direct feedback in the form of comments. If some of those comments are from people I know well, so much the better for me to understand the reason for their comments. Also I can study their other writing before replying to their comments, to likewise understand better. On an external site I expect that many Elliers would not wish to post personal remarks or to make an account to make a comments. I have looked at a couple of such external blogs of people I know here and they are wonderful works of writing - but the comments are few, anonymous and generally short. "Well said - Anonymous." doesn't give me anything beyond the little upper that someone actually took the time to say anything at all. By comparison, personal threads and blogs here at Elliquiy overflow with feedback and discussions. That is part of why I love this place. The 'minors' issue does not really concern me at all since I want to talk about bdsm things like philosophies, definitions and relationship issues rather than bodyparts.
My current plan is to start a normal thread in On Topic, and change the topic line as I go from one blog post to the next. It is not perfect as it will be messy when people refer to older post, but I don't see a better alternative at this point.