Short vs. Long 2x Barlow

My aunt owns an Orion StarBlast 4.5 reflector.

http://www.telescope.com/Telescopes/Dobsonian-Telescopes/Mini-Dobsonians/Orion-StarBlast-45-Astro-Reflector-Telescope/pc/1/c/12/sc/28/p/9814.uts?refineByCategoryId=28

As she has gotten older, using her short eye relief EPs has become increasingly difficult and uncomfortable for her. She asked me if there was something that could be done to fix this problem, and that's when I decided to get her a 2x barlow. But, when it comes to choosing between a long or short barlow, I've been unable find any conclusive information on which would be better in a F/4 telescope.

Any help and words of wisdom would be greatly appreciated.

Depends on the eyepieces she is using... But for a compact scope like the Starblast I would recommend a Shorty, a long barlow would put a lot of leverage on the focuser.

You might consider some new eyepieces as well. The 9mm Synta Widefield (Orion Expanse, AgenaAstro, Owl Astro among others) sell it, it can be had for under $40 and it is good eyepiece in a fast scope and has reasonable eye relief. Combined with a GSO shorty as sold by Agena Astro, she could have a 9mm, a 6mm ( unscrewing the front section of the barlow and attaching it to the eyepiece) and a 4.5mm.

Jon