Hi Neil. I own a Silhouette Cameo 2, does everything that I ask of it but if I was in the market for a new one I’d get the Cameo 4. I can’t really comment on the Portrait series, I think they are a smaller version of the Cameo but others here may be able to speak further. Whichever model you decide, you’ll find that using one enhances your modelling in many ways.
Max