There's not a large amount of benefit - for me it was just the desire to help support the site. What you do get is:
- Access to a "Members Only" section of the forum where recently, for instance, pre-planning for next year's nationwide meet started before opening things up to a more public discussion, and
- Expanded storage for Private Messages, increasing from 50 to 250 messages.
I don't recall that there's any expanded image storage per-user, though there might be - the membership list mentions 40MB image storage. If you click on the blue
SCOA CLUB at the left, it will list items off. The "exclusive giveaways" happened for one or two months before going stale. Many other small items are lightly used.
Oh - there may be inline ads that go away if you're supporting; perhaps that's just for not being signed in as guest. It's been nearly a year since I was just a regular visitor.