I have a smooth black and I don't feel that it scratches really easily. I don't baby my bags either. I've worn mine for a month straight and it's been great! Not sure about the new grainy leather though because I haven't seen it yet, but I like both, so I would be happy with either one.
I love grainy, but smooth does hold up a bit better. If you use the mini luggage as an everyday bag the smooth leather does eventually slouch a lot too. I saw a woman carrying it on the streets and was so shocked at how slouchy it became.
I just recently got a mini in the new grainy leather and I loooooveee it! It's lighter and a bit stiffer than the old pebbled leather & I love the fact that they decided to put feet on the grainy leather mini's now too.
I'm a low maintenance gal & hate bags I have to "baby"...so the grainy leather was a total no brainer for me.