I'm not convinced by microwaves (I still worry about the long term effects of even a small amount of radiation) but the slow cooker for chutney sounds like an idea. It would be interesting to make the same chutney by the different ways and compare the flavours. As Livinhope says I would imagine the slow cooker method may make the flavours more intense, although perhaps not with all chutneys. I like my tomato chutney to be cooked as little as possible so that it keeps as much of the fresh tomato flavour as a chutney can.