I have not noticed any, but I only have 7 Insteon switches, dimmers, outlets and micro dimmers in use at the moment. You have more than that in just sensors alone. I don't own enough Insteon devices to stress test it. I started out with Insteon, but then realized the limitations of their hub software and saw no progress. I moved to Wink and ran two separate systems, then SmartThings and integrated everything and now HE.
A little from both column A and B. I first integrated Insteon by tying HomeKit automations to Virtual Switches. That seemed to work at first, but I soon found that automations often failed to turn switches off, or they would bounce off and then back on again. When Chris helped with the drivers, things became much more stable, but I still had an ON/OFF switch that is used frequently in our Kitchen, fail to operate, or it would still bounce on and off, or vise versa. Once Scott Kuester released the stand alone Express Server, I found that running it separate from HomeKit gave me 100% reliability. I do find that some of my lights lag behind when I run my Goodnight routine for example, so it's not like normal Insteon where everything turns off at once, but it's not that big a deal to me since everything does turn off every night as expected and turns on as expected.
So pursuing the sensor compatibility wasn't a high priority and time was short. With no other Insteon users asking for it and other projects we both wanted to work on, it has been sitting idle and unexamined. I began to discover inexpensive Xiaomi sensors. Tried a few and they're really impressive. Even though they don't follow the Zigbee spec 100%, they work great thanks to drivers created by @veeceeoh for HE. Until recently, their range was an issue and if they were too far from the HE hub, they would tend to drop-off and would have to be paired again or prodded into reconnecting. But we now know that Xbee devices and the new IKEA Trådfri outlets are compatible repeaters for them, so I have even less reason personally to pursue Insteon input devices. I live in a small house, so my issues with Xiaomi devices were minimal, as everything I own really has no choice but to be fairly close to my HE hub. However, I did have the occasional issue. Since adding two IKEA Trådfri outlets as repeaters, I've had no issues at all with the Xiaomi devices. So now I just order them when I need input devices because they're small, very nicely designed and solid performers thanks to the repeaters.
Having said that, I do have an Insteon leak sensor and an open/close sensor that I wouldn't mind putting to use. And if there's someone else in the community that can benefit, it's worth taking another look at. There's a possibility Chris says, of using Web Sockets to get sensor status. I'm not a dev and don't know how to code. I'm picking up some basics, but very slowly. My role in all this has simply been an alpha tester for Chris, since he doesn't own any Insteon equipment.
