I've been using RSS Mix to aggregate the comments and post RSS feeds from my site, then using Feedburner to publish the aggregated feed and email digest updates from the preceding 24 hours. Most of my users rely on the email digest to get update on the site and due to the nature of the site it is pretty important that people do not miss out on any updates.
The issue I look to have is that the aggregated RSS Mix feed can take a while to update which can result in the Feedburner emailer missing content. This had never happened until a few weeks ago where it happened 3 times in 10 days and I noticed all the missed comments were made at the same time of day, but on different days.
Are there any plugins for WordPress that are able to aggregate RRS feeds so I don't have to rely on a 3rd party to keep them up to date?