Streaming recorded content by the native DLNA function is adequate, and an early bug in that streamed recordings would not get past the 4GB point has been corrected in later standard firmware. On the HDR-FOX enable content sharing (Menu >> Settings >> System >> Internet Setting >> Content Share = On), and on the HD-FOX use Media >> Storage (blue) >> Network to access the HDR's content.
Playback of recordings using CF enhancements is achieved using network file access rather than streaming, and means you can manage the recordings as if they were local (bookmarks, fast forward and rewind, resume where playback last stopped, move, delete, etc), but it does require CF at both ends (to enable network file access and also to decrypt the content - which is essential for this means of access but not for DLNA streaming). The original motivation for network file access was to sidestep the 4GB bug, but the additional facilities are quite handy.
There is no need to be concerned about warranty - although caution was appropriate a couple of years ago, we have never yet heard of a case where the CF could not be removed and the unit restored to factory condition.