I understand I am a bit too late, because you have already bought the 56, however I share my experience in case someone else wants to know.
I bought an ACA1230/28 with the purpose of using WHDload on my 1200. It works just fine and I am happy with it.
It takes a few seconds to plug it and so far I haven't faced any issue with it. One (small) drawback is the trap-door cover, that needs to be cutted for creating room for the new board. IMO a worth-buying card :-)