As title says. Ships would have to lose a mid or two and gain a high or two, while ships that are already full of guns should see some hardpoints removed in favor of fixed damage or ROF bonus.
There are two main plusses I see: for say ECM ships, jammers ARE the main weapon - why not put them on highs then? Secondly, those same ships have to ditch tank to fit jamming. Now they will be still greatly constrained because of resources taken by jammers, but at least slots will be available.
As a side change, in general shield tank would be boosted due to many modules formerly occupying those slots are now on highs (for ships that used to fit ewar; others have modules just moved for no net change). Finally, this change will force change towards ships with more utility highs.
(with that change, cloak could become a midslot module - no effect on other ships)
As for drawbacks - I don’t see any conceptual ones as most ships could retain their fits, just with few modules moved in a way I believe makes more sense. The main problems would come for PVE shield tanked ships due to loss of few mids, but I think Gila nerf wouldn’t hurt either.