I'm not sure I can fully answer your question. I have one bass strung with EP weich and two basses with Tempera. The Temperas are worth it to ME because my mother left me some money when she died four years ago, so I can afford to indulge myself (I often think that my instruments are crying out for someone better to play them).
I felt competent to answer your original question because I had JUST replaced a set of EP with a new set of Tempera, so the differences and similarities are fresh in my mind. There was nothing wrong with the EPs; they had awakened that bass after a fresh setup and some other strings that didn't work, and they performed well for the now-ended orchestra season... very close to the sound I want.
BUT I had a fresh Tempera set lying around waiting, and I was pretty sure that I would get a similar sound out of them with a bit of a bonus in comfort and volume. I'm relieved that I was correct. They still haven't quite stabilized, but I have no plans to try anything else on that bass... anytime soon.
So, I guess my advice is: Unless you have the coin to spare, try the Pirazzis and know that Temperas are very much like them. If and when you're ready, you can make the upgrade. It's a common truism that we spend much more time and money getting that last 5%.
By the way, the biggest pain in buying Temperas is not customs; it's the payment process. Jan-Ole doesn't accept credit cards or PayPal, so the payment process is kind of byzantine.