This isn't quite an answer (not enough rep).

Not having experience with the two products you listed but plenty with ASP.NET, I'd say this problem sounds way too generic for a framework to address, no?  Not sure if to say "generic" or "specific".  I currently follow the less-then desirable approach you laid out: store errors on a db /w certain fields and display to the user.  What I don't do but can extend to do is allow the user to select an entry and have them fix it.  It's the "fixing" part that sounds too generic for a framework to do.  Only you know what "fixing" the error means within your context and can program for that.  In this case, give the user a webform to update the data and save it.  I could see how the two products you mentioned can help in reporting the errors but still feel the rest requires a custom touch.

Reporting and handling asynchronous process errors to a client
I have some waypoint layers that contain different types of points and I distinguish these in QGIS by different symbols and colours.  I want to export these to a GPX file that I can download to my GPS but The GPX file contains just the lat, long and the 'type'.  

Is there a way of getting gpstool to save other attributes in a gpx file?

I do get some more data out in  (gid, source and classification) so I can write a script to process the xml and add the necessary attributes that the GPS expects.

Secondary question:  Would this make a useful plugin?
