If you are fairly certain that you prefer the Maggie sound and will want to upgrade to the 1.6's in the future, then save yourself some hassle later on and buy something now that will drive the bigger speakers when you get them. Frankly, if you heard and loved the NAIT, which I believe is about a $1500 integrated, then you should try to audition it with the 1.6's, and if it works, just lay out the extra green and be done with it. That way, you know it will continue to sound good, and you won't have to take a hit upgrading the amp along with the speakers later. But if it's not powerful enough (a real possibility), try to spend about the same amount used if you can, because the 1.6's will need the quality power.
BTW, just a note about some comments above: Maggies actually have a very benign impedance characteristic - 4 ohms, which is ruler-flat compared to most dynamic speakers, and just about purely resistive in nature (as opposed to reactive), meaning no tricky phase or capacitance issues. They are, however, a relatively inefficient design by nature, meaning they suck power in order to go loud or do authoritative dynamics. They are also, unfortunately, quite revealing of the sonic flaws inherent in most lower priced amplifiers (not so much a problem with the SMG's, but it will be when you get the 1.6's, which brings us back to my preceding advice). Also, I own a C-J MV-55 (a great amp), and though they do make an integrated version, the CAV-50, my experience with Maggies tells me that if you like bass or high volume levels, this will not be a match for you. Better to stick to Philjolet's SS recommendation, but just beware about what may be revealed if you try to pick up an older SS model for low $. (I've heard Maggies chew up and spit out a "300w" Adcom, and then turn around and sing with a "100w" Audio Research SS. You'll need the power *and* the quality, I'm afraid.)