I have a 401 in the T-rex and a 240 in my Axe. here is a my reply when I ask the guy who help me build the T-rex:

you can get a GY240 gyro (almost as good as the 401 you have...but, not
quite). with the 240 you don't need the remote gain wire to take a
channel, the gain is adjusted on a pot right on the gyro. then, you can
use the free channel for your retracts. however, the cost of the 240 is
right at $100, you will lose the superior heading hold function of the
401, and extra resolution of the digital S9650 (though it can still be
used--it just won't be running in digital mode).

regards,
Crash