Quick update for those following my recent problems. Since I removed the older Sengled outlets, and swapped them out with the newer models, things have been pretty solid. The lighting has been cooperating perfectly, and the re-paired Aqara devices have been staying connected. One of my temp sensors may be bouncing on and off, or the temperature has just stayed steady for multiple hours (to a day) at a time. Haven't dug in enough to know for sure honestly. All of the other Aqara devices have been staying connected from the looks of things though. I'm guessing the driver change has helped with that. Jury is still out on Aqara devices cooperating fully, but so far so good!
About a week ago I was able to get the Ikea blinds re-paired to the hub. Tried the 'hold an inch away from the hub' method, and they all connected and were receiving commands after pairing. I was able to get an Ikea repeater paired as well, and stuck it between the blinds and the hub, in the same room as the blinds. The night I paired them, one was a little iffy, and took a couple commands to get it to go up/down. Though, ever since, they have been responding as expected. Think it just needed time to realize it should be using the repeater, rather than a direct link to the hub.
I did notice a couple times the last couple days walking into my kitchen a Smartthings motion sensor I have wasn't triggering the cabinet lights on. A dashboard command / or remote button command seemed to get the lights to come on, so I am thinking the motion sensor is acting up. Might just be a low battery honestly, I haven't had the time to diagnose. Hopefully I'll have some time in the next couple days to dig into this a bit more.
Also, just a side note: over the last 1-2 months I had slowly been cleaning up my hub, in terms of unused resources. Removing no longer used virtual devices, uninstalling unused apps and drivers, and cleaning up other things I used to experiment with, but never ended up fully deploying. Not sure how much of a difference it made, but I know there were probably a couple apps that were using hub resources that didn't need to be. If anything, it just helps the hub run more lean and efficient.
Overall, things have been cooperating much better than they were a week ago. Not sure if it was just the older Sengled model outlets causing a fuss with the mesh, or (most likely) a few problems stacked up making things not happy. But, between removing the older Sengled outlets, swapping out the Aqara drivers, and giving things time to settle, it seems to be working quite well.
Thanks to everyone who pitched in with advice, this community never fails to disappoint! 
