$US2400 cheaper and almost 1kg lighter than the Sony kit but it has 1 EV less shallow DOF
carrying the telephoto zoom is far more comfortable than the Sony 100-400 with the camera and lens weighing only 1.2kg compared to just over 2kg for the Sony option
alternatives:
Olympus 12-100mm f/4
Olympus 40-150mm f/2.8 760g $US1149
Panasonic 50-200mm f/2.8-4.0 655g $US1699 close focus 0.75m
Sony a7III + Sony FE 12-24mm f/4 G + 24-70mm F4 CZ + Sony FE 100-400mm f/4.5-5.6 GM OSS
better eye AF tracking, but ergonomic / menu issues
option for much more expensive and heavier f/2.8 zooms but no affordable options beyond 200mm focal length
f/4 full frame DOF thus 1EV shallower DOF and perhaps 1EV better image quality if don't need the deeper DOF
24-70mm is very soft away from centre at all focal lengths even on stopping down and has a complex distortion pattern and uses 67mm filters
alternatives:
cheap kit lens: Sony 28-70mm F3.5-5.6 OSS $AU329
Sony FE 24-240mm f/3.5-6.5 OSS $AU1350
Sony FE PZ 28-135mm F/4 G OSS $AU3399
Sony 70-200mm F4 Sony G OSS 840g $US1499 but has soft corners even stopped down and is soft in the centre wide open at 200mm and obviously doesn't get to 300mm like the Olympus does, or to 400 as does the Panasonic
Sony FE 100-400mm f/4.5-5.6 GM OSS lens $US2498 1.4kg close focus 0.98m
single super zoom travel kit
Olympus E-M1 Mark II + Olympus 12-100mm f/4
weight: 574g + 561g = 1135g (25% lighter)
cost: $US1199 + $US1199 = $US2398
the Olympus lens gives the best optical results for any 8x zoom lens ever made
unlike the superb Olympus lens, the Sony lens has poor reviews for build quality and optical quality - satisfactory up to about 100mm, beyond that it degrades quickly and by 150mm it becomes very soft with poor resolution and contrast.