Sorry for the delay in responding, I've been re-jigging my mesh based more realistically around the kit I already own, which is mostly AlertMe gear. But yes, even before this revamp, that's pretty much where I was at.
My mesh is now:
2x AlertMe Buttons
1x AlertMe Keyfob
1x AlertMe Lamp
8x AlertMe SPG100 Smart Plugs
1x Ikea Trådfri 400lm E16 Lightbulb
1x Xiaomi GZCGQ01LM Light Sensor
2x Xiaomi WXKG03LM Wireless Switches
Those '3LM wireless switches would drop from the mesh within 90 minutes - until I added the Trådfri lamp to the mesh. Now, though none of the Xiaomi devices have ever routed through it, they stay connected and have done for a couple of days. Remove the Trådfri lamp and they drop within 90 minutes again. Weird.
For whatever reason the GZCGQ01LM light sensor has never dropped from the mesh, even before the Trådfri lamp was added. That thing has been perfect, which gives hope for the future seeing as it's one of their new Zigbee 3.0 devices.
Because I can find no better alternative for UK light switches my plan is to acquire another hub which will run only those devices with Trådfri repeaters, which I have plenty of now that I have a working mesh that doesn't use them. 
Actually, I'll probably throw one on this mesh regardless, just in case the lamps (there are more to be added) are ever powered off accidentally. Because all AlertMe repeaters have battery backup (it was designed as a security system) it's sensible my link to the Trådfri world be battery-backed as well.
