I'm afraid I know nothing about the new XML Publisher capabilities in the upcoming 8.97. Sorry.
When we first implemented XML Publisher, we noticed that some files would error out without having been processed. After going round and round with Oracle Tech Support, I finally noticed that it consistently errored on the larger files, somewhere after 100 KB. What it really was, was the timeout value on the JAS server and Enterprise server. This was set at 90,000 milliseconds, or 1.5 minutes. The file would take longer than 1.5 minutes to process, and the JAS server got tired of waiting. The file was actually still processing, but had nothing still waiting for it to return. After increasing the timeout, the have been able to process all their check runs, and so far all of them have been under 500 KB in size. The only effect I noticed was that the JDENET_K kernel for the XML Publisher used about 100-150 MB of RAM, as opposed to the 30-50 MB of RAM normally taken by a kernel.
While researching the issue though, there were mentions in the Knowledge Garden of known bugs in the XML Publisher for .XML files that were much larger than ours, 20 MB to 50 MB in size.