The combination of RPCEmu and RO5.2x on XP has been in daily use from 24/10/2013 (two months as at 2013-12-28).
For the author this follows a previous install of 0.8.10 upgraded from 0.8.9 with RO5 in use from early 2012
Note 1: RISC OS 5 beta versions are updated frequently with nightly builds from the CVS but may contain bugs so important data should only be trusted to the stable installs.
Note 2: RPCEmu is deemed alpha quality by its authors, which rather negates any comments about stable installs in note 1. In practice, many people use RPCEmu without issue.
If you have no need for networking stop here. (details coming soon)