I finally took the plunge and listed on HomeExchange.com in June. I didn't get any positive responses to my inquiries. I did get inquiries from several people including one or two in Italy, that came to nothing and I had decided to forget about the whole idea. Then just this week, on Monday, I got an inquiry from a woman in Paris and within 3 days we agreed on a swap for 2.5 weeks in April. So I guess I'll stick with it for another year and see what happens. I'm not the best case because there are a lot of offers here in Israel that I'm "competing" with.
It cost $120 for a year. You can browse the listings all you want. If you see some that are interesting, get a 2-week free trial which lets you contact them. I haven't used any of the other companies. This one seems to be very trustworthy. You can see how many exchanges the owner has done in the past, read some reviews from people who've stayed in the property. As with the other companies above, this site is basically a match-maker. There is online chat available if you have questions. They've been very helpful when I've needed it. . . sometimes I've found it a little tricky to navigate the site.