The 175 is very similar to the 105 in terms of radio/PHY hardware (both are 2x2:2). Client density support could be the same depending on the area of coverage. However, if you are doing this outdoors over large ranges with higher gain antennas, that same rule may not apply since your clients will be more spread out, and would be running at lower rates, possibly have issues where clients cannot hear each other and creates some hidden node issues, etc.
Horsepower-wise they are similar and in low-coverage/high-density situations, they should be the same. Outdoors at much larger distances, that may not be the case.