I write this as someone who was against sleeving from the get go.
We bought Rotr back in about August, since then we have played through it five times so it has gotten quite a bit of use. The cards are taking quite a beating between chipping, bending and peeling back. Going into S&S we again decided not to sleeve and about then we realizd just how worn RotR was. Now into adventure 4 we are again seeing a good deal of wear showing.
When we started the season we decided to sleeve. Granted it is now a pain having he game box unsleeved and the class deck sleeved, we carry quite a few extra sleeves to keep up. But having them sleeved is keeping the cards in tact. Long story short, when wrath comes out, we'll be sleeving. Just need Ultra Pro to get their insert released or Broken Token, here we come.
As for sleeves we have tried three version and we recommend the ultra pro ones. We have penny sleeves that are cheap but work well for tracking skill and power feats. The Fantasy Flight ones were next, quality was nice but they are a bit too long and got annoying when shuffling. Finally got the ultra pro ones and we stuck with them. It's a small difference in length, but enough to make a difference imo.