Does anyone know the numbers on the pre rework speed add ons for legion?

I would disagree, they can be quite nice in trying to line up an approach that blocks LoS before the person catches wind that you're pursuing them and starts looking for you.

Incorrect. While the situations you may run into will vary in terms of how you should pursue the chase, you can assess if they're inside or outside your TR based on if you actually hear the heartbeat sound or just see the indicator. Given that the maximum range add on is 16m + 32m TR you're talking 48m, which is within legion's travel distance. Now it is up to you to use your knowledge of the map and where exactly they are likely on it to assess if it's a worthwhile pursuit, but unless the person is located in some sort of winding structure you should be able to reach their present location. This is without duration add ons, which you should be running on legion since they're probably his most useful add on and not accounting for the increased range of frenzy due to the run speed buff.

I suppose you could argue that could happen if you doubled up on detection range add ons, and you'd be right. But I'm not suggesting that is a good idea.Considering a good portion of chaining hits are about positioning yourself so the survivor cannot see where you're coming from until you're reasonably close so that they can't run out your duration, knowing where they are before they even know you're in range of seeing them is a nice early advantage.

In terms of the iridescent pin, for the most part yes I'd agree. The detection range ones are a bit sneakier and can catch people off guard multiple times a match, compared to the iri pin which lets them know immediately that you see them and could potentially be moving for them. It also has the potential to mislead you as to the plausibility of a target. So it isn't a clear cut better in every way sorta deal, but pallet breaks being built in is quite nice as well. But it's also worth noting that it is an iridescent add on and as such not something you'd run every match.

On a separate note, I think it would be nice if legion had the option to do a slow vault that broke the pallet, similar to how demo and oni have pallet breaks that are about BS speed. Given that killers have this ability that are potentially lethal right after breaking the pallet, I think it would be reasonable to give a guy with a 4 second pause before potentially downing such an ability, and it would help him make the map unsafe quicker which is something he needs due to being only M1 downs.