In my opinion, people who just have an A500 will take a lot of advantages of this device.
People here who bought one of those babies simply put their A1200s in semi-retirement since playing with the A500 is better!
Also, A500 IDE/SCSI controllers are very expensive and memory expansions (but the internal A501) are expensive, too.
In a final note, to make a decent WHDLoad machine based on one A500 you need:
1- Fast memory (at least 2Mb, better 4Mb, 8Mb is excellent);
2- HD controller. SCSI is widely available for A500, some few IDE ones. For SCSI then an ACARD board, plus a Compact Flash adaptor and the CF itself;
3- Optional 3.1 ROM to be able to run ECS games on the A500 (ECS Denise is not necessary, just the 1Mb Agnus).
All those bits and bobs costs money. So you can't have the HD-expanded A500 for less than 200USD!
The floppy emulator wins!