This is interestinq question. I did some tests. Test algorithm for 1 iteration:
- Open data source. (Db connection for Linq to sql. Prepare isostore and streams for reading/writing xml and json)
- Prepare new MessageModel. All message text have 150 char.
- Apend new message and save it.
- Release data sources.
Table below show results for 1000 and 10 000 iterations. Tested on emulator.
In yours scenario - I don't think you'll have many records. If u don't need any complex query and update etc. XML is good choice. It is easy to use, the resulting file is readable and don't need any third party library.