Seems like it should be possible to put one together that works well at 6v.
I'm finally taking the LR carto plunge. I should be getting a handful of 2 ohm cartos this afternoon. I started with the boge cartos for reference and plan on getting some of isaac's LR cartos to compare. I'm most keen to try the IKV LR901 carto, but also the 510megaLR.