Nexus 30
Hey there.. If you can get the Nexus, go for it.. I have two, and have found it to be a good trainer. I have about 4 gallons of fuel through my machine, and I took the training gear off after starting the third gallon. It is a relatively stable machine for a helicopter, if you follow the manual very strictly during setup .
As for the Gyro, personally, I run a Futaba GY 502, with a Digital 9250 servo. Don't overlook this or blow it off as "oh, I need one of those things too" (to quote the Nexus manual). The gyro in your heli is your lifeline, and insurance of success when flying a heli! Lose it, and you are more than likely goin down! Consider the gyro/servo as a reusable component assembly, and plan on using it in your next machine as well.
I researched the Futaba line (I use an 8UAP in heli mode..), then asked questions about all of them to a friend who flys helis. He prefers the Futaba GY 401 w/ digital. I settled on the 502 w/ digital, for the extra programming functions available to me (again, looking ahead). You NEED a good gyro if you want to be successful with your heli, and a fast servo is conducive to a steady tail when learning.
Two points to watch... If you get a gyro that is Digital capable (able to boost the frame rate for digi servos) use the appropriate frame rate for the servo being used. The second point is from a longevity standpoint. Gyros will tend to "eat" standard servos. The tail servo is constantly correcting the yaw attitude of the heli, to compensate for wind, torque, etc. This means the servo is almost always in motion, unlike in a fixed wing a/c. Get a servo that is fast (for tail response time and to fully utilize the benefits of the gyro) and on the same hand, a quality servo meant for gyro use. Your wallet will appreciate the long term benefits of this initial investment!