I’d go 3mm, but I probably wouldn’t be able to see the little buggers well enough to get paint on them. 
What do they bring to the party that 2mm doesn’t? The group I was in then had a fling with Irregular 2mm back in the 80s. The armies all looked a bit…lumpy on the table.
"I go online sometimes, but everyone's spelling is really bad. It's... depressing."