Good question. Is there a source for suppression values? Gbem doing one-off experiments isn't exactly data.
Fire arc vs set-up time is entirely subjective. I find set up time to be a lot more important than fire arc, because my squads can crawl up to an mg34 and grenade-wipe it easily. Doesn't work for mg42 because you'll get pinned way earlier. For 50 cal and Maxim you can actually dodge grenades, and continue to stay in the fight by packing up and re-positioning. MG34, once dislodged, will not have the opportunity to re-position and set up again.
The quick tear-down time also factors heavily into survivability. When I use 50 cals, it's very common to get Vet 3 on them, but MG34 crews face a much bigger risk of being wiped because they take so much longer to pack up.
you are free to test it out yourself aswell... use cheatmods and a timer... sample size of 5 is generally enough... both must fire without obstruction on a target without any cover... target must be at maximum range and in both cases a conscript squad
you know whats not subjective? 3 barifles vs an MG34 and 3 LMGgrens vs maxim.... those barifles will get suppressed in a frontal charge... yet 3 LMGgrens can solo a maxim frontally
you are correct about teardown time though... it is indeed very important... but the deathloop is far worse than long teardown times... and ive lost more maxims to the deathloop than MG34s to its teardown time