Yeah, the connection method...it's just eeeeeaassssyyyy.
(just don't drop your allen wrench across the busbars!
That and the easy-to-package cell format...If I had money and they were local (battery shipping is a PITA) I'd buy these as spares (though I have plenty for now, it doesn't hurt to have spare packs), or to use as a solar storage system (if I ever get any panels).
What are the voltage sag limits you're after under load?
BTW, you could use the A123 pouch cells the same way, but first you have to weld brass (I think) tabs to teh cell tabs like the EIGs have, they're "folded" at 90 degrees just before the holes for the screws.
You could also 3D print frames like those the EIGs use, but sized for the A123 pouches.
But the only source I know of for A123 cells that I'd trust is the manufacturer, and they're expensive (and dont' come with any mounting or connecting hardware).