I had a Zephyr, and loved it. I use a lot of sound equipped engines with the higher functions, so I sold the Zephyr, and bought a Zephyr Xtra. I've had nothing but problems with it. In fact, it is on its way back to Digitrax for the 4th time as I type this (delivery day is Tuesday). It has given me hours and hours of headaches. Multiple calls to tech support, and problems galore. So much so, I went out and bought a DB150, which has been a vast improvement.
So, long story short, unless you are using engines with a lot of sound features, try to find a NOS Zephyr (DCS50), rather than a Zephyr Xtra (DCS51). It will be more than enough for any small layout.