Moving drivers around is ok in theory, but usually the driver has the configuration (tuning) done on it and moving it from one machine to another will result in less than optimal tuning for that machine. Also there is risk of damaging a drive if you disconnect it while its energized.
The reason I went with small servos is as Arizona mentions - you can only get so much out of a gecko drive (or equivalent). There are lots of other drive options out there - you just need to shop around for them. For DC servo drivers Viper drives is one, CNCdrives is another - now sold thru cnc4pc.com CNC4PC, DMM tec as I showed earlier is yet another (AC drives)Servo products