Since I reported an error with Transcend 133x CFs in the past I can say the following...
Upon power on, you get the classic Kickstart screen but with a single reset (Ctrl-Amiga-Amiga) the issue is solved. Any reboot from that point doesn't have any problem. Only power on this issue occurs.
AFAIK that is a really common issue that exists to some users and depending on the CF or HD they use.
With Sandisk's simple CF you don't get this issue and no reset is needed.
ACA1231 is working great and the new heatsink gets only slightly warm. Nice job on that one Jens!