I've had an eclipse avn-2545 in my gs400 for over two years and recently put a z-1 in my STi...
The touch screen and boot up time is quicker in the eclipse and the all over build of the eclipse seems a higher quality to me... design and feel of buttons and crafmanship of the z-1 seems cheaper to me in my IMO..
However, the fun factor blows away the eclipse... 3d mapping, nav traffic, ipod control, voice recognition,hard drive and blue tooth blow away my now boring eclipse..
the z-1 sounds great and has much more audio parameters to be set... i have a focal component speaker system powered by a 400 w arc audio amp and the z-1 sounds awesome.. i'm also happy with the sub control of the z-1.. with the addition of a bass attenuating knob i really can fine tune the bass with the z-1..
the only gripe is i'm still waiting on the blue tooth adapter after a month.. i already paid for it through my installer and can't wait to get it put in.. iv'e read so many mixed reviews about the BT and can't wait to find out for myself..
the z-1 fits so perfect in the STi you swear it was factory..