Wish there were 2 REL's in the house but there's just the one.
When the crossover frequency is set really low it seems to add a nice bit to the low end without messing with the mids or the dynamics.
Here was my thinking ...
You've said that a good setup for a distributed sub would be a 4th order crossover set around 60 hz (give or take). That slope would be down 24 db at about 120 hz.
Assuming the REL has a 2nd order crossover and it was set at 60 hz before. The slope would be down 12 db at 120 hz, hence there was too much energy from the rear sub.
Setting the REL to crossover at 30 hz would make the slope down 24 db at 120 hz. Similar to a 4th order sub crossed over at 60 hz.
Sure, there will be a difference between the energy output of the 2nd order slope and the 4th order slope over the same frequency range. But by 120 hz wouldn't they both be reaching the point of no return?
Is this a correct interpretation of what's happening?