I managed to get an A500 a few months ago and was a little disappointed with the lack of expansion options out there for it so I will be interested in getting on of these for it. The A500 already has an IDE controller in it but it is old and slow (but still better than disk ony) but the disk itself is dieing so the CF Disk option is nice. The A500 I got also already has 8Mb of RAM (1Mb as Chip) so I would be interested in seeing if the RAM on the ACA500 will cause problems with this.
Also, the chance to get the A500 on my LAN is good. The only other option I could see was finding my old PLIP cable I made years ago. Will make getting new software onto the A500 a hell of a lot easier.