As others have said, light is important. The only complete failures I've seen are people trying to grow them inside without enough light. 6hrs sounds great - but by default my growing area gets more (south and west facing, north Texas).
Habeneros are a type I have not tried, primarily because we wouldn't be able to find a use for the fruit. They are cultivars of a different species of pepper to most other types. Most are Capsicum Annuum cultivars. If memory serves me correctly, Habeneros are C.chinensis, so their growing requirements might be a little bit different (eg. see my other question about C.frutescens cultivars). Basically what I'm getting to, is to try and find a good seed supplier (I can recommend the one I use but I'm not sure if the forum should include such commercial references) and try some different varieties. There are pepper types that have been bred for cool weather, high heat, low heat, etc. Some of the northern ones might do well with less sun.