Yeah, the RM emphasis on +20% and +30% damage RMs is going to increase a lot (it's already relevant as of now, I don't use +ATK RMs when I'm running Shout anymore), while those for offensive magic are an effective waste of a slot. Physicals are better equipped to survive the pendulum swing than they were back at the age of 340 attack cap (i.e. when mage meta reigned supreme and non-synergy 5* rods dealt double the damage with -jas that synergy physicals dealt with Pound) or even mages are right -now- because being resigned to Focus for stacking buffs to MAG blows chunks.
EDIT: Also, regarding mults at base themselves: I have the internal assumption that the mults on magic still ended up accruing higher -base- damage than physicals' - for abilities at least - before any buffing is applied, all other matters equal, for most of the 4* abilities. Before the mass RES hike, a synergy Firaja, for instance, still significantly outdamaged a synergy Pound. Until 5*s and SSBs, the mult difference was still skewed in favor of magic, mainly due to the glaring leap from 3* mults to 4* (-gas hovered around 4.9x and 5.3x while 3* physical abilities hovered in-between 1.8x [-ra Strikes] and 2x [Launch]. -jas jumped straight to a 9x mult while stuff like -ga Strikes and Pound were stuck with 2.1x-2.3x mults. The strongest 4* ability, Bonecrusher, is a single-hit 2.8x... that deals 25% mHP to the caster).
The burst attacks on Terra and Bartz follow roughly the same spread (10x mult on her attacks, 2.5x? on his). It was most notably glaring for me on a U+ Vargas setup that, under Shout and Apocalypse Shield, Bartz' fire attack did about 25% more damage than Terra's Fire attack in spite of Terra -not being under Faith-, only the Burst +20% boost. That's some interesting interplay at work there, showing mostly the effect softcaps has on offense.
THIS SAID, the gap has closed a fair bit on the 5* abilities (3.4x-4.4 to 11.8-13x, for instance).