I am currently making a short list of add-ons for the EX3. I wonder whether the following filter will fit, without getting in the way of the lens hood. If anybody has tried this and could let me know whether it will fit comfortably, I appreciate it.

B+W | 77 mm Kaeseman Circular Polarizer Slim Glass | 66025844 (http://www.bhphotovideo.com/c/product/181590-REG/B_W_66025844_77_mm_Kaeseman_Circular.html)

This one is 3 mm thick.

A more general question is whether to go for a UV filter B+W | 77mm UV Haze 010 (MRC) Multi-Resistant Coating | 66026942 (http://www.bhphotovideo.com/c/product/132978-REG/B_W_66026942_77mm_UV_Haze_010.html)
or a Clear filter Hoya | 77mm Clear Pro 1 Digital Multi-Coated Glass | XD77PROTEC (http://www.bhphotovideo.com/c/product/391169-REG/Hoya_XD77PROTEC_77mm_Clear_Pro_1.html)

The clear one has no other function than protection of the front of the lens, the UV has a dual purpose, protection and UV reduction, which is nice on water and in the mountains.

All suggestions are welcome.

Go with the B+W MRC UV slim.