I also own a Tempest 170 Pro that I use for trips. At 5' 10" and 190 pounds it seems pretty huge to me and I only use it when carrying another 130 - 150 pounds of gear for distances. In my opinion the T 165 is a much better day boat at our size though, for me, the T 165 isn't as easy to get in and out of.
The T 165 is a great boat and having spent a lot of time in both it and the Z 155 I found that I preferred the Z. Lots of differing opinions out there on that one though. I sold the Z to help finance my Illusion which paddles like nothing else for me. Since getting the Illusion my bar has been raised a bunch and I have paddled a Z160 poly and a T165. The Z 160, while too large, still felt special while the T 165 felt fine but ordinary. The Z155 paddled much better for me than the Z160.
It really comes down to what your aspirations are and what you need the boat to do for you. Every boat is a classroom. What class do you want to take?