It depends how much you're looking to change your system. I'm a fan of the new 1500 (all CPU's have PN built in), but it might involve a lot of re-work to take advantage of some of the new features. If you switch to a 314C-2PN/DP (
6ES73146EH040AB0), then the engineering changes would probably be minimal. You could also buy a CP343-1 and add it to the 313C you are used to using, but that solution isn't as straightforward as upgrading to a PN cpu.
I like working with Profinet compared to Profibus. It gives you more flexibility for how the network is laid out, and I seem to be spending less time troubleshooting the physical network. Instead of assigning a profibus address to a device, often via physical DIP switches, you now assign a profinet Device Name. This can be done either via the engineering software or with separate stand-alone programs.
Profinet is also nice because you don't need a Profibus converter dongle anymore, you can connect to everything via Ethernet, which laptops already have. The main "trick" is that you typically need to assign a static IP address to your laptop that is in the same network range as the devices to which you will be connecting.
The Primary Setup Tool (PST) is a great tool that allows you to browse the Profinet network to see what devices are there. It can assign both an IP address and device name to each of them, and many can also be reset to factory defaults.
https://support.industry.siemens.com/cs/us/en/view/19440762
