I'm sitting on the fence. There are a couple of things that do bother me.
1) Value of a forum
... is pretty much wholly created by the members who contribute the ideas, information, and opinions. The forum owner (in this case you) and admins provide the means that make that happen, but otherwise do not create the content. Content, which is the sole basis for why FC has been valuable to many, has been created by the contributing members, who are now being asked to pay.
This bothers me, because a countless number of posters (past and present) have volunteered our ideas, tips, opinions to make FC to become a valuable source. Yes, many of us have done it partly to gratify our ego, but it is also true that many of us actually wanted to be helpful. I know that many may not agree with what I write, but still, I believe my opinions have forced them to re-evaluate their own beliefs, which is a good thing.
Thing is, I didn't do it to profit from it myself, nor expected someone else to make money on the tips and ideas that I or others provide.
2) Intellectual property
As Cheryl asked earlier, I wonder who owns the copyright of the posts published in a forum. This question is not just academic, because with a paid membership, Strider will be "selling" the aggregate value of these posts that have been and will be created by members.
I have done a little search on this question, and my tentative conclusion is that original posters are implicit copyright owners. By posting in a forum, however, s/he grants the forum owner a license to publish, edit, delete them. What is not clear is if the forum owner can profit from these materials.
3) Expenses
I understand that there is an expense involved in hosting a forum. What I do not understand is $100/yr/person. With possible 2-3,000 paid subscribers, you would be raising a few hundred thousand dollars. I don't believe that Strider has been absorbing this much every year.
It wouldn't have bothered me, if the fee was a few dollars a year per subscriber. That would raise perhaps as much as several thousands a year, sufficient to pay for hosting (actual cost without profit) as well as aspirins and pack of beers for each moderator. Yes, you and admins would still have to work for free, but contributors too are working for free also.
4) Projects
The point #3 above brings up another issue: what are you going to do with the money raised? One way of looking at this paid structure is that members are being asked to invest money on your projects, the details of which are not clear to me.
-----
I just wanted to be candid as always.