xml feed parser from multiple sources, multiple url-source xml importers
To me this seems like an exact use case for Feeds plus Feeds XPath Parser.  It will be possible to map your custom XML spec to various fields and import content from as many sources as you want into nodes of the same content type.  I posted an answer to another question which may give guidance on how to use it.
Feeds:


Import or aggregate data as nodes, users, taxonomy terms or simple database records.

One-off imports and periodic aggregation of content

Import or aggregate RSS/Atom feeds

Import or aggregate CSV files

Import or aggregate OPML files

PubSubHubbub support

Create nodes, users, taxonomy terms or simple database records from import

Extensible to import any other kind of content

Granular mapping of input elements to Drupal content elements

Exportable configurations

Batched import for large files



Feeds XPath Parser:

Feeds XPath Parser is a Feeds plugin for parsing XML and HTML documents. It enables site builders to leverage the power of Feeds to easily import data from complex, external data sources. Each element you wish to extract is setup using configurable mapping queries, saving time for developers who would otherwise have to code complex, specific-use modules. It also enables end-users to build web scrapers and other useful tools within Drupal.