Bi-wire: is it worth it?

I ran a pair of bi-wired Nordost Heimdall 1 speaker cables about a year ago or so. So Nordost did used to make bi-wire cables. I'm not aware if they stopped making them.

Nordost still has 4Flat biwire speaker cables in their product line. I wouldn't be surprised if the other lines could be ordered that way.

Here's bi-wire Frey, but notice it's on closeout. Maybe Nordost is going single-wire for their upscale offerings.

I agree with the above. I do have the SL3 in the family and recall that that crossover design benefited from biwiring. I think the old Stereophile review of the SL3 recommended biwiring. I have mine externally biwired with twin runs of DH-Labs Q-10 Signature.
That being said, other ML's may not need that even if they do accept biwiring. I believe alot depends on the xover and also how an amp senses and reacts at a given time to the woofer vs. the stator impedance through 2 different cable runs combined at the amp end. May want to borrow an extra pair of cables or a new biwire set and judge.

I have read that Nordost has stopped making internally biwired cables due to the inherent compromises, but has revamped their line of biwire jumpers.

Kubala-Sosna makes excellent speaker cables. I am a dealer for them but you will have to contact the manufacturer to determine who you nearest dealer is.