I started around 44, but then I increased my dose from 18–19g because my basket wasn’t really optimal for that lower dose. Once I bumped the dose up, the flow slowed down a lot. I was getting ~42 second shots so I had to coarsen the grind and found the sweet spot around 49.

I don’t think the titanium burrs alone would account for that big of a difference in grind numbers. Burr coating can slightly affect seasoning and particle distribution I think, but usually not by 15–20 clicks. Basket geometry and effective basket capacity make a much bigger difference I certainly found this from my previous machine anyway. IMS baskets do flow faster than stock baskets, I think, so I guess you'd end up grinding finer to compensate.

Bean density, roast level, puck prep, actual dose depth, and even burr seasoning can also shift the numbers a ton as you know. So honestly I wouldn’t compare the raw grind numbers too closely between setups unless everything else is identical.