Comparing a 15kHz converter with the indivison aga is stupid.
Or can you do that ...
http://amigasys.ultimateamiga.co.uk/amigasys5-amiga07.jpg
Maybe and maybe not. For workbench work you don't need any of the devices and just use one of the Productivity modes. For games it doesn't matter as they are low res anyway. For those who need PAL to NTSC conversion for games the 15kHz converter is actually pretty convenient, especially if you have additional 15kHz computers (ZX Spectrum, Atari, C64, etc). I'm not taking anything away from Indivision, but both products have its purpose.