I had the Z3200 and then downsized to a P800 after moving. From my perspective the Z3200 was a dream machine with the exception of size, fan noise, and the disintegrating carriage belt. I didn't have any problems with the interface (don't remember it being problematic). For the fan noise, I just turned the machine off when I wasn't printing.
I guess you need to decide how large you want to print first. I switched to the P800 (17") and I mostly use it for proofing larger prints that are going to the lab. It is an amazing printer that has the smallest footprint in the 17" class. But it hasn't been as trouble free as my old Z3200 (occasional clogs, paper loading issues).