Thank you everyone who replied!
Just wanted to post a follow-up on this now that I've returned - my trip was incredible, and I had almost no problems with vaping in Israel.
I was traveling for several weeks, so I brought a lot of equipment - several 30ml bottles of juice, cartomizers, 6ml tanks, a ProVari, and some eGo and 18650 batteries. Most of it traveled back and forth in checked baggage, which caused no problems or additional screening.
On the way there, I had my ProVari in my carry-on, which did catch the attention of the U.S. TSA agents at every security point I went through. After the 1st time, I put it in the bin with my laptop and told them it was an electronic cigarette. They swabbed it and sent me on my way. On the return to the U.S., I packed it and took only an eGo in my carry-on, no questions asked.
While I was there, I publicly vaped anywhere people were smoking analogs - cafes, hotel patios, on the street, in the courtyards at work. No hassles at all, only the occasional friendly question about what it was and how it worked. Smoking seems like it's still pretty common there, so I often had company to chat with about it. I didn't see anyone else with a PV, but I don't commonly see them in person here either.
Finally, I'd be doing a disservice if I didn't say Israel was an absolutely amazing place to experience. There's ancient history to be seen and touched, incredible food to be eaten, great shopping and people watching to be done, and wonderful company to be enjoyed. English speakers will have very few issues getting around or communicating. Street signs, most shops, and restaurant menus are in English, as well as Hebrew and often Arabic. Most people speak fluent English as well (and seemed happy to do so). Driving in and between the major cities was straightforward - outside of distances being in Kilometers, it's essentially the same as in the US. Last, given the relatively small size of the country, you can stay in one of the major cities and see most of the sights either within the city or on a very easy (1-2 hour drive) day trip out and back.
If you have the chance, go there at least once, it's simply amazing. Oh, and bring your PV.