I've never seen a dovetail plane or saw. A couple of years back my friend traveled to PA to look at some classic repro furniture. I don't remember the place he went to but it was somewhere in the Lancaster area. He was disappointed a little in the quality coming out of the place. High end stuff, nice wood and nice prices but the final fit / finish just wasn't there. He was especially disappointed that they offered a distressed finish if the customer wanted it. Trying to make stuff artifically 200 years old. Just not his style. He just couldn't see a colonial cabinetmaker doing anything short of his darned best to make a piece as perfect as he could. And that was the only way he would build anything. Let time and use create it's own distressed finish. They even went to the extreme of artifically cresting watermarks from drinking glasses.
I've never tried a sliding dovetail. Might look into it and see if it's something I may give a go at doing. I guess I've never built a piece where it would have been useful. We'll see.