I use the Wahl switchblade and OLD OLD Osters And do lots of scissoring ....
so the Wahl KM2 is fine then ???nope, they work FINE on a 10 blade! it's the 40 blade that it screws up. They do work *better* over a 30 blade though, as that's what they're designed for, but I use mine over a 10 all the time too. And yes, the stainless steel combs are AWESOME. lol.
IMO you won't need two speeds Jak. I only use the single speed ones at work day in and day out! I use a 2 speed one when I'm down in balclutha every week, and it's not going to make any difference for you really, just go with the single speed unless you really want the different accessories!