Among many other speakers through the years including ATCs, Epos, Apogees and Martin Logans, I have owned and enjoyed Magneplanars since I was a junior high school student in the late '70's - from MG-Is to Tympani IVs which I still have today.
Personally, I would never try to combine a dynamic subwoofer with any of them - regardless of price or quality.
I would first consider your room, and experiment by moving your 1.7s closer to the front wall and/or corners.
You can use blue painters tape to mark the positions and may find that even 6 inches will make a significant difference.
At the same time, you can experiment with pushing your listening chair closer to the rear wall.
Unless its your thing to rock out with hip hop or heavy metal, even the smaller Magnepans are capable of rich, magical, three dimensional sound, hence their enduring business and reputations with audiophiles.
In my experience, the people who speak poorly of them are generally dealers who don't sell them.
Cheers,