I have it on good authority that the 15 hour requirement was omitted from FCL-2 and thus LASORS in respect only of helicopter instructors due to a typo.... involving a whole missing paragraph.
My quick reading of Change 4 doesn't necessarily suggest that the 15 hour experience requirement will be reapplied. In any case, the whole issue is up for discussion at the forthcoming CAA seminar. My personal view (and I have been instructing/training SE/ME in a variety of environments since 1980) is that there should be an experience requirement for Restricted instructors, though not necessarily as much as 15 hours. For all instructors, if it is the first type of a class: eg, after conversion from SEP to SET (or vice versa!) they should have perhaps 15 hours on the first type in class before instructing, but a lesser requirement for subsequent types in the class. After all, assuming that the current type rating requirement is (Change 4) reduced to 2 hours plus the test, it would be reasonable to spend a further few hours flying the aircraft from the LHS and undergoing a check (in LPC format?) in the LHS. This could, however, be a FTO/TRTO administered check, with Head of Training approving the instructor's competence to fly and instruct from LHS on the recommendation of a FE/TRE.