I have been holding off on getting a 17 TS-E because I've got the Lee 100mm holder and a bunch of filters and having to start over with something like the Wonderpana is not attractive to me. I read that you had toyed around with the DIY adapter made from a spare lens cap. I know the biggest limitation from that setup is the lack of shift; did you find that shift was limited so much that the 17 TS-E was not effective when using the adapter and holder?
I've made the DIY set up and I dislike the limitation in shift. With the WonderPana their is no vignetting.