As someone who values the information on the forum but only sporadically posts, I thought I'd offer my thoughts on this topic. First of all, I suspect that charging for basic access to the forum will eventually kill the long-term development of the forum. This is covered above.
Second, I don't see any problem with charging for certain "premium" content. In my mind, this could include the e-magazine and/or additional articles/resources. Frankly, I would suggest removing the archives from the "free" part of the forum. Then, ask someone (?) to edit those materials into more user-friendly segments. This would become the initial "premium" content. Maybe portions of the books could be placed in the "premium" content as well.
I think most people would much more readily accept advertising than subscription fees.
Additionally, I would like to chime in along the same lines as Brettski. If the site moves to a paid site, I think its important to clarify the focus of the site. I very much value the information on managing fish. This is clearly the focus of the expertise of many existing forum members. However, there are many pond-related topics that really are not covered in detail by the existing materials on this site. Having recently built my pond, I am currently struggling with issues regarding the best marginal and emergent plants for around the pond, tranporting trout, building an outdoor patio/kitchen, and how best to build a walkway to get through some wet areas. There is some information on this site, but much of the information I've found comes from other sources. I think any move to premium content should be accompanied by a concerted effort to clarify the site's focus and perhaps expand the range of "premium" information available. If you Google "Ponds", you will see that most people interested in "ponds" are not actually focused on fish. If you Google "Fish Ponds," you will find that people interested in fish ponds are often focused on koi or other ornamental fish. I don't have a garden pond or a koi pond, but I do sometimes visit those sites to get information to help manage my "pond."
For my part, I would pay a subscription fee for the same reason I subscribe to the magazine--it will be worth it for me and I'd like to support a site that has supported me. I would not have done so at the outset. I like the print copy of the magazine, but am not wedded to it. I probably would not buy the print copy if I obtained an e-copy as part of a forum subscription or other fee.
