8x10" polaroid film has been discontinued for a while, but shortly after it was discontinued, the price became astronomical, so I sold off my 8x10" Polaroid processor and filmholders. It was a beautiful material.
Here are more 4x5" shots on my flickr site, though none shot with the Sinar (mostly with a Linhof Tech V, one with a Linhof Tech II, and I've also used a 4x5" Gowland PocketView)--
Here are a few more 4x5's on my website--
And also this page is all handheld 4x5" work with the Linhof Tech V and a strobe on a bracket--
This was made with a Linhof 6x7 rollfilm holder on the Sinar 4x5" sliding back on the Sinar 8x10-->4x5 reducing back on the 8x10" Sinar P, which sounds insane, but I kept the 8x10" Sinar P set up all the time on a studio stand at the time, and swapping formats and configurations on a Sinar P is a very quick operation--
Here's a crop from an 8x10" on Ektapan made with the 8x10" Sinar P--
I prefer large format film over smaller formats and digital for most things, but I use what makes sense in any given situation.