I've got a Boss DS-1 too.
They're good pedals for boosting leads if you've got the sound in mind but just want more boost before it hits the pre-amp without really shaping the sound highly noticeably like a Tube Screamer would. Joe Satriani and Steve Vai really come to mind here, as they like (or at least, have in the past) used DS-1 pedals to get a bit more boost and compression out of leads.
For heavy rhythm guitar, not quite as useful unless the amp is already tight on its own. Better to stick to Tube Screamer for most heavy rhythm stuff.