The subrepeater is also the same size as a carbine. Literally the only use for it is as an automatic pistol for those that don't have Rifle proficiency (i.e. Scoundrels and Nobles), or else as a weapon to let a Small character use braced autofire... which isn't that great, and a single talent can let you brace selective fire weapons, again making the subrepeater inferior to a carbine.