gamm

I am new to Houdini and would really appreciate some advice regarding the Houdini > After Effects workflow.
My usual workflow involves rendering multiple file sequences from Maya and compositing them in Adobe After Effects. I would normally render a Luminance Depth pass, Shadow pass, Specular pass etc.

I am using Houdini on a project for the first time; and we started by rendering .exr images with extra image planes from Houdini and extracting the channels in After Effects, but I found that the files made AE so slow that it was unworkable.
We then tried rendering tif files and saving the image planes as separate file sequences. This is fine for the beauty pass, but the Zdepth pass would need to be created as a greyscale image to be useable (I understand that tif files dont have a zdepth channel). We also found that many of the tif files were unreadable in After Effects (they seemed to be corrupted / half written).
I am basically hoping for some advice as to a workable Houdini > After Effects workflow. What file type would be best (tiff, tga, 16 bit interger, 16 bit float etc?)
Thank you in advance.