I also tried a MicroArranger but didn't like it. It had the already-outdated interface of the Pa50SD combined with tinny on-board speakers and mini keys. At the same time, Korg was making the Kross 1, which had FULL-SIZE keys, similar or less weight, and was only about two inches wider overall. Total missed opportunity!
A couple of small and light hardware arrangers that I know of are: the Roland GW-8 (13 lbs, no built-in speakers), and especially the Casio CT-S500. Don't laugh!! It's one of the newest, and probably best entry-level arrangers currently on the market. (To edit styles you would also need a more advanced Casio arranger in your studio, or third-party PC software to convert Yamaha styles for use in the CT-S500.) The manuals are online, and it should be readily available for auditioning in Texas stores like Guitar Center. If you're willing to go up to 18 lbs or so, the Yamaha PSR-SX600 is loaded with TOTL features in a compact package for a pretty modest price.
An alternative approach would be a lightweight 61-key controller and arranger module like the Roland BK-7m ($) or Ketron EVM ($$$$). Final option would be a controller and arranger software like Nimbu or Giglad running on a notebook PC. Lots of variables and ergonomic challenges with software that I wouldn't want to deal with for live gigs.
Many of my friends play portable "campfire" instruments, so I've struggled with the same question for years. I would love to wear my keys for door-to-door caroling at Christmas time, etc. I actually bought a GW-8L for this purpose, but selling it because I'm convinced the Casio is a smaller, better choice. Try it, you might like it!