Do any RSS apps available for OS X and/or iOS sync via anything other than Google Reader? I recently switched from NetNewsWire to Reeder on my iPhone and iPad because a) Reeder as a “Mark as unread” button, and b) I thought NetNewsWire was marking older articles as read, and not letting me switch them back.

I soon realised that old articles were being actually marked as read because Google Reader does that after a month.

Whilst I prefer Reeder’s UI, I think it’s (currently) purely a Google Reader front-end. Are there any RSS apps that sync via some service, free or paid, other than Google Reader, and thus let me keep articles as unread for more than a month?

NetNewsWire used to sync via NewsGator, but I believe NewsGator no longer offer an RSS sync service.
My last comment just gave me one idea that might solve your issue: Google's Feedburner. You can configure it to send emails from any feed. It will be little troublesome at first as it's a long manual job. Seems like it is unsupported and not really meant to be used like this. But it works perfectly!

Here are some quotes from its own help:


  What triggers the email to be sent out?
  
  FeedBurner sends subscribers a daily
  digest of new content from your blog,
  so a new post, new title, link, or
  change to the published date will
  trigger the email delivery. If you do
  not post anything that day, no email
  is sent out.
  
  FeedBurner only keeps a change history
  for items currently listed in the
  feed. Once they “drop off the bottom”
  of the feed, the system forgets about
  them completely. If you re-introduced
  them later by increasing the number of
  items your feed contains, this will
  result in the newly included items
  being delivered via email as “new”
  content.
  
  How much does this service cost and what methods of payment are accepted?
  
  FeedBurner Email is a free service.
  However, we do accept voluntary
  payment in the form of props and
  general goodwill.
  
  How do you get started?
  
  Sign in to your FeedBurner account,
  select your feed, navigate to the
  Publicize tab and select "Email
  Subscriptions."