Probably MGs would shine more if there were more developed rules for suppression fire and more of an advantage to a larger ammunition capacity which would probably mandate higher rates of fire for all weapons across the board to make reloading more of an issue.

well, you can kind of exploit this with multiple initiative passes. lay down suppressive on the first pass, then switch to burst fire on subsequent passes. you can only really do this once or twice with an SMG or assault rifle, but you can get three good rounds of this out of a 100-round belt before reloading.

SAWs and .50 cals are not the same. One is anti material one is anti personnel. One is designed for moblity the other is made to stop trucks and other mechinized equipment.
I will stand by my original statment of they are not designed to be shot at people. I'm not sure why this is controversial to you. Anti material was the design goal.

Except with an smg i can suppress then the next pass longburst as a simple eject the clip and reload. Not a huge loss in economy of actions.

I'm not sure you can combine supressive fire with firing normally like that:

"The suppressive fire zone lasts until the end of the Combat Turn as long as the firer does not move or commit to any other action." - pg 179

In my read, opening fire on a specific target instead keeping an area suppressed counts as committing to another action.

right, so the suppressive fire zone and penalty goes away when you start doing something else other than the suppressive fire, but you still do inflict the penalty until you do start doing something else. the idea is you suppress the enemy for the first one or two passes they have, reducing their effectiveness at return fire, then take your last one or two passes to make concentrated fire to finish off anybody who is wounded in the initial suppression or who is an obvious threat. it's a big advantage for being wired enough to get multiple passes, and if you must commit to suppressive fire for the entire round that would go away.