I think that requiring green packs for large mining sites is too excessive. Maybe it was intended to require blue ones?
Also it seems to me that research Mk2 and Mk3 gives the same results (large & extra large robot mining sites)

Green science packs (in Vanilla Factorio) is the second available science pack. I think you mean the yellow ones (Utility science packs).
This shift happened when updating from 0.16 to 0.17.
Changing the utility science pack to the chemical science pack (the blue ones), isn't something I'm going to do, as the robot mining sites have nothing to do with science.
Though I guess you have a point for utility science packs might be too expensive, so I'll probably add a setting in this weekends update to change the utility science packs to production science packs (purple ones) as I think they fit better.

Science pack changes are included in the 0.9.7 update.
As of the two researches you mentioned, the first one grants the ability to produce large and extra large mining sites, while the second one lets you upgrade smaller sites into larger ones.