The initial met results don't tell us what the particle size...

The initial met results don't tell us what the particle size distribution is from crushing and grinding. For all we know they might have attempted a very coarse 3+mm to feed the HMS/DMS, and determine if they could achieve a very cheap processing route.
If you looking into the work Nagrom's have completed for others, they have gone to 100-300 microns to achieve 6% Li2O with Flotation. Some have gone lower than 100 microns.

One thing they all have in common is that they all claim to potentially be low cost producers. Which attempts to say that the additional Grinding and Reagents cost is immaterial.

They upside from here is higher concentrate grades, higher recovery rates and lower impurities. i.e. Higher sales volume and revenue.

The downside, more POS plant mods (and cost), slightly higher opex.

The net result, well I'll take higher sales volume and revenue at the expense of slightly higher opex when margins for this product are so high.