I'm playing my first vanilla game in a while and went to outfit an Onslaught. No Storm Needlers were on the map, so I decided to give Mjolnirs another shot. Gotta say... not too bad:
The light needlers work amazingly, and the Mjolnirs have such good accuracy that my sides are very well protected. Their flux efficiency is truly terrible (I do think a small buff would be nice...) but their damage output, accuracy, and turn rate make them just murder on smaller ships for as long as you can fire them. Can't really fire the TPC's and the Mjolnir's at the same time, so I'd recommend turning the Mjolnirs off when engaging frontal targets (until out of TPC charges).