As someone with no WRs or stake in the discussion, my thoughts:

• the original reason to separate makes sense (community consensus); as someone who wasn't there at the time I find it hypocritical to second guess past decisions
• community consensus can change, if folks now want them to be merged - it could go up for a vote; I personally would limit the vote to people who have actually submitted runs, not everyone who watches (ie. myself)

IMO - the easiest way to handle this is to make a JOINT Any% Deathless hybrid board that you could submit to, in addition to the SC/HC board.

Assuming the consensus was to allow HC runs to filter into some new Any% Deathless hybrid

• moderators now have a 3rd board to manage; I would offer folks should have to submit to both boards they are eligible for - don't place the burden of categorizing on the mod team.
• there really shouldn't be any issues with increased workload for moderators, it's pretty easy to tell if HC runs finish

Assuming the consensus was to allow SC runs to filter into some new Any% Deathless hybrid

• same first point
• THERE IS a large verification burden (i.e. watch the whole playthrough for deaths) that I expect to impact the verification speed... all the moderators are volunteers and have limited time they can devote to critically analyzing runs that can and have gone 52+ hours (https://www.speedrun.com/d2lod/run/z014099y)

The real question to me is: Do we see any value in having a joint Any% Deathless board on top of SC and HC boards?