The AP-365 is not a replacement for the AP-275. The AP-275 is a higher powered AP with 3x3 11ac. The AP-365 is a lower cost, slightly lower powered unit that is 2x2 11ac. The range, capacity, etc of the 36x is expected to be approx 80% of what the 27x is. So if you still need max performance, rate v range, high user counts, etc, you should still use the 27x.