Non-repeating Zigbee devices should not be impacting your mesh unless they are bombarding it w/excessive activity and/or have a very noisey driver, which I doubt they are/do.
Aqara devices in general are unlikely to hurt your mesh more than any other device, unless similar issues w/noisey drivers that are generating excessive traffic or errors due to calls to deprecated features. I run Aqara on my C7 & C8 and do not have issues w/them causing problems. On my C8 they have actually been more reliable than Iris v2 motions and Visonic contacts.
I'm mostly using this one for my Aqara contacts.
What settled my C8 down the most seems to be repeaters taking the load off the hub...in recent testing I've determined that pretty much all of my Zigbee battery devices on my C8 are routing through repeaters rather than directly connected to the hub. My best repeaters are SonOff USB dongles, Tuya USB repeaters (the tiny ones), Iris plugs, & Ikea plugs. C8 power is set to 8.
During the time when devices were repeatedly failing to stay connectd on my C8 (and oddly, this was led by usually very solid Samsung/Centralite leak sensors, Iris v2/v3 motion sensors, and Visonic contacts) I moved those devices back to my C7 and hub meshed them back to the C8. That seemed to be the other key part of things settling down and I've been running pretty much issue-free since then. ~90 Zigbee on C8, ~35 Zigbee on C7. Stock Zibee antenna on the C8.
I did do an antenna mod for Z-Wave on the C8 - it sorted some issues I'd had forever on the C7 and to less extent on the C8 w/some Z-Wave iBlinds that had trouble communicating once in a while to the hub. The antenna (Bingfu 4G LTE RP SMA Cellular Antenna 7dBi Outdoor Antenna) provided solid connectivity (the iBlinds are communicating through the metal housing of my blinds) and they have been perfect since.
