I own a Pronto. Yes its a nice scope but it really nothing more than a fancy achromat with "phony ED glass" and big brothers that are APOs. From what I understand the Megrez II is not much better.
It seems to me that the clear choice in this class is the Orion ED80, it seems to offer APO performance according to many who have tested it.
I'm not a refractor person, but consider to acquire one of the three alternatives discussed here (Megrez, Pronto, Orion ED) for low power wide field use. My question is therefore: Which alternative would you choose if you never were to exceed a power of 100x, and only use the scope for DSO's?