self-watering containers or heat mats?

I am starting seeds this year for the first time (tomatoes, peppers, some annuals - nothing too complicated). I was very interested in the self-watering systems from GSC and Lee Valley. However, both say that they're not for use with heat mats. I've been reading about the magical qualities of heat mats - lots of people say they wouldn't start seeds without them. My guess is that the self-watering containers are too well insulated for the heat mats to actually heat the soil. So, is it true that they don't work together, and if they don't, which is more important to have?

A lot of the self watering systems are made out of polystyrene. They hold water well and capallary mats do well with that since the part that holds the soil doesn't have a bottom and the capallary mat conducts water right to the soil. The polystyrene (think foam coffee cups) is fairly thick to be durable and for heat from a propagation mat to get through would be impracatical. Heat transfer one way or another is minimal.
Ambient temperature is not as important as soil temperature, but in a warm room, using the cover the self watering systems will maintain an appropriate growing temperature so long as it is not in direct sun.. If the ambient temp is low, >65-70oF the mat would be a better choice. The final decision is determined by the temperature requirements of the seed. Check the germination guides such as Thompson and Morgan. Jessamine

Thanks jessamine!

I'm starting the seeds in the basement, where it's fairly cool, so I think I'll go with the mats. I'll check the Thompson and Morgan guide for the seeds I have.