Technology is such a huge investment that you want to be sure you’re getting precisely what you need. I’ve never tried the Surface Pro, but I’ve been using the iPad Pro, Apple Pencil, and Procreate app for two months and am completely in love with them. The Apple Pencil and Procreate app seem to work together flawlessly, with zero lag (an issue which seems to be a common problem with many other styluses). Pressure sensitivity works perfectly, allowing fine hairlines and wide swells. Procreate brushes (essentially pen nibs) can be modified or created from scratch, so that you can write with precisely the effects you want. I have a few favorite brushes for pointed pen, as well as some I’ve made for Italic and broad edge work, and they work very nicely. (If you’d like me to send you a sample of writing, just PM me.)
Give some thought to what programs/apps you would be using (and whether they’re available for the device you’re considering), as well as the effectiveness of the stylus you would use. Those will be huge factors for your artwork; you don’t want to discover after the fact that what you want or need isn’t available for your particular device. Can you go to an Apple Store to put the Pencil through its paces? (Sadly, if they don’t have Procreate loaded on their iPads, you won’t get a sense of what you can do, calligraphy-wise.). Can you try out a Surface Pro in a similar fashion? That might be the best way for you to decide what will work best for you and your hand. I would buy the iPad Pro and Apple Pencil again in a heartbeat -- but keep in mind that I’ve never tried the Surface Pro, so have no basis for comparison.
LindaR.