So after realising that 'lower tuning' isn't synonymous with 'heavier tone' I've started to think about what the best low tuning for OSDM would be. I say Old Death Metal in particular because, lets face it, it's the best.
My first mistake was buying a 14-68 set for my 27" ESP EC-401B and thinking it would go down to F standard without any issues and then getting a 13-56 set to go to B. This was too tight for all but for the low B, which was at pretty much perfect tension so I needed to go to A# to get the tension I was comfortable with but then that put the B out of tension just enough to make it too muddy.
While playing around with these string I found that personally I wasn't too keen on how the thick (ish) 56 felt, even at perfect tension. It wasn't comfortable for me. It also made me consider the timings that most of my favourite DM bands played in and realised that they never went lower than about C#/C Standard but still sounded incredibly heavy.
I'm planning on getting a 12-54 set and going to C but wand to get some other two cents before I go. I know it's all personal preference but I think it would be interesting to hear some of your experiences.