I haven't done any mass reads or writes, but both the Catweasel Mk3 and Mk4 work wonderfully for me when I need to do ad hoc imaging.
The Catweasel is just a piece of hardware, however, so you'll need to tie it to a good piece of software. The card comes with a very basic imaging program. Jens is/was closely involved with the Arjuna project, so that might be a good place to start as well. In any case, yes, errors are reported to and handled by the software. Speaking of Jens, he's always helpful. If you have specific Catweasel questions, try emailing him directly via .
The SPS/CAPS people don't support the Catweasel (see ). If you have a real Amiga, you may have some luck getting the SPS folks to produce IPF image files for you, but I gather they're only interested in getting their hands on commercial software. See their site, , for more info.