I would compare the exersp/dotfit to the bodyfit (Gowearfit) sice it has the same sleep feature.
then I would ask if the sleep feature is important, do think you are having sleep issues like you are up all night? exausted all day? or is it just a fun feature you really want. Only you can dertermine the value.
For me I think they are all about equal so if I were buying today I would go for the best price and I don't think that the extra 100 is going to have it last longer or work better. I would however get the digital display, I think that is worth the $.
No matter what you get we have a thread her at 3fc you are welcome to join.... Bodybugg/Go Fit users, lets keep on track together 4!
OH, and welcome to 3FC