"If the shoe fits, wear it." In this case the shoes are Magnepans and the foot they have to fit is your room. More than any direct radiator except big horns, Magnepans are are best chosen for, or maybe fitted to, the room size they are used in. it is simply in the nature of flat panel dipoles needing the breathing room to properly work their magic. I recently bought and quickly sold a pair of ,7s when it became clear I did not have a Magnepan-friendly space for them. I am no Magnepan hater, far from it, having owned several pair since as far back as 1976.
The current lineup of Magnepans goes from 13" to 29" in width and 48" to 79" in height - variations of over 2X in width and 1.6X in height. These things matter more in dipoles and line source speakers far more than in traditional box speakers because they determine in large part how the speaker acoustically loads into the space. the 2.7i is something like 25% larger overall than the 1.7i, so if you think your room can accommodate them, then do it if you wish. If the 1.7s are a good fit for your room, then I probably wouldn't make the move.