Experimenting with this build now. Makes fun. Some would prefer MLas over SPLas, but you have higher DPS and more Pinpoint at very Close Range. Alternative with cooler LLas: Blagg
Very fun build. You can rack up the damage, but it depends on your play style. If you go assist the main group, you can do quite well ... I tend to go bother other lights or LRM boats who look like they are having too much fun. Many times I manage to delay or harry those LRM boats until more lights or the rest of the crew shows up. If they choose to ignore me, well, that is a dead mech. Very satisfying that.
I've run a similar setup with 2xSLas and two more JJs, but the SLases felt so superfluous. I should try this out.