the hpx170 and hvx200a will look super similar since they have same chips, an improved sensor from the original hvx200. they both will be a little bit wider than the 200 which is super helpful if you get an xtreme fisheye, and are better in lowlight.
the tape deck adds a lot of weight to camera as well, so the hpx170 is a lot lighter than both the hvx200/200a. there are a couple other little differences between the 170 and 200a, like a "delete last clip" function, built in histogram, and extra ND filter, but they will look pretty similar (and a lot better than the original hvx200) since they have the same sensors.