Um, 'slave Replays' to what? The DTivo? Or do you mean 'record stuff and watch it later' (I wouldn't call that 'slaving'). I use RTVs with D* with no problems.
As for D* vs E* (DirecTV vs Dish), that's a whole 'nother thing, with all the new toys due out 'real soon now' from Dish. See the DBS forum for tons of talk on that!
I don't know if the SS's can control new(er) sat boxes. Note that most recent boxes will need to be controlled by IR, if that matters. (But I've never had any IR problems at all with 5000 boxes.)
As for D* vs E* (DirecTV vs Dish), that's a whole 'nother thing, with all the new toys due out 'real soon now' from Dish. See the DBS forum for tons of talk on that!
I don't know if the SS's can control new(er) sat boxes. Note that most recent boxes will need to be controlled by IR, if that matters. (But I've never had any IR problems at all with 5000 boxes.)