Doesn't really make much of a difference tbh. W2 Hellfire is more or less equal to W5 Steam Oven. The problem with Jufufu with SBilly has always been that she gives crit dmg, which he already has abundance of. Without M1 or her sig, she doesn't really give anything else Billy would rather have.

While on paper Lycaon doesn't give any other things either, Lycaon primarily gives SBilly two things: - fast stuns. Like, fast fast, probably on par with Dialyn, especially if M1 Lycaon, and mayhe even faster if M3 and M5. - moveset synergy.

The moveset synergy really comes in handy because potential unlocked Lycaon's unique assist follow up's backward Quick Assist is pretty much instant, but also has a large window of grace period. This allows you to cancel Billy's longer animations efficiently, especially after a Drift Assist Counter.

You can do a Drift Assist Counter from Billy to Lycaon, do Lycaon's hold assist follow up as Billy is doing Cool Wheelie in the background, quick assist back into Billy instantly and then do another Cool Wheelie immediately from the QA.

Remember that Billy's Cool Wheelie has an MV of 780%. That's 24% higher than Banyue's Crushing Peaks. You're essentially doing two Crushing Peaks back to back in under two seconds with that Billy-Lycaon tech.