Differences between and advantages to using Type IL vs Type I/II cement 1

I have never specified Type IL cement or been asked to use it as a substitute for Type I.

This presentation seems pretty helpful. The "L" is for limestone which is permitted to be added to the cementitious portion of the mix.

JLNJ, it's coming. Our company has been developing an approach to IL. The institutionalists (like me), say "...that we've been using the same kind of cement for 50(?) years and know its quirks." But we're tilting at windmills. There's a push to lower emissions and IL has an advantage there. So some batch plants are stocking only that.
They tell me:

Advantages:
[ul]
[li]Lower carbon footprint.[/li]
[/ul]
Disadvantages:
[ul]
[li]Not as much history.[/li]
[li]Limited long term experience. (think ASR)[/li]
[li]Basically combinations of the two above.[/li]
[/ul]

There's probably engineers on this site who know a lot more than me on this, but my view is one from the trenches.