I've never heard of sliding 2, but I happen t know that sliding the thumb works quite well. It's much more important that you have the proper facility of 3, 4, and 5. If those three fingers can move quickly enough then the thirds won't be a problem. Might I recommend you learn Op. 10 No.2 before you learn 25/6?
"I always make sure that the lid over the keyboard is open before I start to play." -- Artur Schnabel, after being asked for the secret of piano playing.