I never came across a synth that was amazing as a synth and as a controller at the same time.
It took me a long time to figure out what type of keyboard/s I like to use.
In the studio I use anything and everything. From a DX7 to an S90 to a wavestation and 01/W etc (I've got about 30 synths and modules in my studio). But when it comes down to live gigs, I use my Roland AX7. Being a guitar player (aside from being a producer) I like to move around on stage, instead of sitting behind ten keyboards. The only downside about an AX7 is that it's really designed for playing with one hand. So if you have to play parts that involve both hands, you'll need something else.
The lightest controller is a Roland A-30 (and later models). That's what I used to play years ago. The good thing about having a controller separate from your synths (modules) is that you can hook it up to whatever (you can obviously do it with your Z-1, but since Z-1 has it's own sound you're most likely to use it's on board stuff. It's a psychological thing. I call it " I payed for that synth, I might as well use it and get the best out of it"). Something like an A30 (or similar controllers) + a module of your choice might be just what you need.

PS
3351 is just a user name. Most people on this site call me Ed.

-ED-