SPL... not so great, but if you want a challenge. Heat 'em up, shut 'em down, take 'em out. 7 x 6 = 42 > 33 = 18 + 15 4 x 9 = 36 > 33 = 18 + 15 36 damage for 25.42 heat (ghost heat included) If you can get away with one less heat sink or the arm flamer, you can get the lower arm actuator which is very, very nice. Since SPL range is 165, try to be patient and not get caught out in the open.
Once people take armor/structure quirks, it may be insufficient. If they're shut down, duration seems less relevant, maybe some heavy smalls could do the trick? Frees tons for MPL in case you can't get close enough.
The TC3 will probably help overcome a few points of armor or structure quirks. Going MPL greatly opens up the range of engagement and helps overall play. SPL are still underwhelming, even in groups. I would lean toward shorter duration, even with head shots. Edit... um yah, just use the MPLs. SPLs aren't worth it with the ghost heat and short range. Would be nice is the ghost heat on SPLs and micro lasers got backed off/desynced, since they can't reach medium range.