I find empreinte quite easy to care for, I just occasionally spray with a bit of Collonil spray. I leave the lock off of my speedy because I tend to zip it to one side when using, and I find the lock is then in the way of the hardware on the strap where it attaches at the side.
I got my noir Empreinte Speedy back in September and have worn it almost every day since then. You have nothing to worry about! The leather has softened a little, and the gold lettering above the outside pocket has faded a bit, but other than that, it looks new. I haven't treated it with anything and have even been caught in the rain a couple of times. Empreinte leather is very durable! I don't wear my lock on the bag because I don't want the extra weight.
Thank you both for the tips! I just took the lock off. Both of you helped me feel a little less nervous! I'm really hoping this will be my (nearly) everyday bag.