Vince: I use the z5500 regularly for playing out in small-medium venues and it works well. If you get it remember to use the PLII music setting.
Big lesson learned for me is the issue of speaker placement. If the rear speakers are not close enough to me I have a really hard time hearing myself play and can get out of sync with myself (if that makes sense). Moving the rear speakers closer helps.
As Gary will affirm (he has been a valuable resource in why to get these and how to optimize), the center channel speaker is responsible for most of the mid-range tones. Personally, I am considering replacing the Logictech speaker with a better speaker for just the center channel to improve the mids. I think something <=$100 used on eBay will do the trick. For the same reason stated above, I have found that I like the center channel behind me instead of next to me sitting on the sub-woofer as some other people do.
For quick setup/breakdown, I have replaced the standard spring-terminal wires that comes with the unit with RCA connectors that I wired to each speaker and made a custom breakout box that I attached to the sub-woofer. It works well. I can now setup/break down pretty fast.
Travel with the unit is good. I put nice wheels on the base unit. All of the speakers, including all associated wires for unit and my keyboard fits in one large gym bag.
For mounting the speakers on stands I have a good woodworking friend who has helped me create some custom mounts to mount the speakers individually on lightweight mic stands and even mounts to attach the speakers to my T2 just like the Yamaha speakers.
Some time in the next couple of days I will post pictures.
I like my z5500. I wish it had fewer speakers to set up. It really needs all 5.1 for the best sound. For the amount I was ready to spend I think it’s the best choice. If I had the budget I would look at the Anchor Audio that you posted on recently. One piece, with handle and wheels, and wireless, and bose-like speakers. That looks sweet. Just not ready to spend the $1,600+.
I think your plan to use it for vocals with a small mixer will be successful.
If you get it and doesn't work for you, it's Gary's fault.