Comparison of Braille Displays

Hi, is there anything published that compares the physical traits of the newest pocket sized braille displays? Or does anyone have hands-on experience with several? For example, how does the Focus 14 Blue stack up to the Perkins Mini 16 vs. the APH Refreshabraille 18? Which one fits in a pocket the easiest? Which one gives the most pleasant reading, typing experience? (Subjective, I realize.) What other displays under 20 cells are available? (While I welcome any info, for my purposes I consider displays that are 24 cells or larger to long to fit in a pants pocket.)