Tempering your chocolate for slabbed ganache

Hi - I was re-rereading one of Peter Greweling's books tonight and he really emphasizes using tempered chocolate when making slabbed ganache. I never use this method as I use so many different chocolates when making different ganache recipes. I would never have the time to temper them all.  He says it makes for the creamiest consistency. I use the warm cream method over finely chopped chocolate.

Anyone use his method out there? Or has anyone tried just melting chocolate to get out all the crystals and then adding their hot cream?

Thanks!

Megan