I am all the way with you Dutchie, up to the mkII for panic situations ;-)

SIB increases your HA and dmg potential in relation to non-SIB. I am not sure what scopes and lasers do HA and speed-of-gaining-skills-wise.

But this led to the following strategy for me:
opalo
opalo+a101
breer m1a+a102 - switched when maxed
breer m2a+a102 - switched when maxed
.
.
.

Reason not to switch too early to the breers is that while your HA is OK, your dmg potential and reload time is awful. If you are not careful the breer will have near full HA, but has a damage potential of an opalo with an even lower dmg/sec because of the reload time.