Notes: In my opinion the Consular is the smallest and most ergonomically comfortable Apprentice hilt.
Fast Facts:
Length from blade retention screw to emitter lip/LED screw to emitter lip/top switch to emitter lip
Acolyte/Disciple: 3cm/6cm/11cm
Arbiter/Sentinel: .5cm/8cm/13cm
Bastion: 5cm/7.5cm/10cm
Chosen: 3cm/NA/NA
Consular: 4.5cm/8cm/13.5cm
Oracle: 3cm/6cm/11cm
Why do these numbers matter?
The length between the emitter lip and the screws for the LED/blade determine how securely the blade rests in the hilt. There is a great deal of design diversity in the Apprentice line which means that both the length from the blade retention screw to the emitter lip and the length from the emitter lip to the LED retention screw are equally important depending on the hilt. For example, the Arbiter/Sentinel's blade retention screw is located .5cm from the emitter lip. However, the blade slides into the body of the hilt a good 6cm-7cm to rest on the top of the LED (8cm in). The Bastion, on the other hand, has a blade retention screw a good 5cm down the length of the hilt which is very close to the LED retention screw (7.5 cm in) where the end of a blade would rest on top of the LED. The Chosen, since it's a thin-neck is completely different from the rest. It's emitter supports the blade which is surround by 3 cm of the emitter.
Finally the length of space from the switch to the emitter lip gives DIY'ers an idea of how much space they have to work with for their cram/careful-fu. The interiors of the Apprentice's are stingy with space so this is important information to consider.
General Thoughts on the Apprentice Hilts: I firmly believe that the Apprentice line contains some of the most comfortable and versatile hilts that SF offers. While there may be a great deal variety of design in the Elite line you'd be hard pressed to find an Elite hilts (with some exceptions like the Gladius) that is as reliable and comfortable as an Acolyte, Arbiter, Consular Disciple, or Sentinel. The "new kids on the block," the Bastion, Chosen, and Oracle, are responses to customer feedback for a more durable thin neck and cues taken from popular ASP designs (ex. the Oracle's emitter closely resembles emitter 10). So whether you're considering an Apprentice hilt as your "starter" or looking to populate your saber stable with a workhorse the Apprentice line offers some very attractive, affordable, comfortable, and versatile options.