I bit the bullet and bought the Enhanced Willem Programmer (regardless of what I had read about them) and this particular programmer worked fine for me when burning kickstart roms using 27C400 eproms. I tested an eprom in my A500, A500+, and A600 and they all worked fine. I haven't tested one in my A1200 yet as it requires 2 eproms. Will test this soon as well.
Useful note: If you read a kickstart rom chip into the eprom programmer and want to use it in winuae you have to perform a "swap BYTE" operation and then save the file.
This eprom programmer will also come in handy for programming eproms for my C128 and Plus/4
PS. If you do have a choice between a USB only powered willem programmer and one with selectable power options i.e dual power, choose the dual power one.