1/3 less time with the 5955's. Regarldess of the battery you're running. Same weight for both servos though.
2400mah at 4.8/3000mah at 6.0 stall
5985 spec sheet
http://www.hitecrcd.com/product_file...2/HS5985MG.pdf
3400mah at 4.8/4200mah at 6.0 stall
5955
http://www.hitecrcd.com/product_file...IFICATION..pdf