David, I looked through pictures of some of my vases and really feel your vase is FT c. 1910. Prunts were popular at this time, so you probably just have a good example of a vase outside the normal range. Many of my pieces have also had thin rims.
It is difficult to research FT. Even the company doesn't know if they made certain pieces. Sometimes they are helpful, but usually not, in answering questions. Leslie Pina's book is good but limited to a small range of the pieces produced by FT. (It also has a couple of AVeM millefiori pieces thrown in.) I stumble across most of the information I get on FT when I'm looking at auction catalogs or similar things. If you find a good source of information, please let me know. I wish there were catalogs.