Hi, we've been using Cimatron here in our mold shop for ca. 10 years now. I've only been here 3 yrs. though - in this time we've gone from e8.5 to e9 to e10 to e11.
I've actually never heard of it13, what year was it published? from the screenshots I see when I do a search it looks pretty old - 10 yrs?
to answer your question- If you can afford it go for it! e11 is way better than e8.5 so I can only imagine what the difference to it13 will be. e11 is so powerful and pretty and visual and fast it will blow your mind. We do high-powered injection mold design, our code runs to 1-2 million lines regularly.
what do you do? if you just do 2.5d job-shop stuff e11 though fun is way too powerful you'll never use a 10th of it's power. then you may as well save 10k and get mastercam.