Also what causes the lockups and need for reseting the current miners, is it in the chips themselves or the interface circuitry.
The miners itself, as well as the usb hub are definitely not the problem. I've connected them to a Raspberry Pi, running cpuminer it's rocksolid!
No lockups at all. Right now I'm testing this with cgminer which looks very promising.
Another nice thing to know:
First I used the original PSU's. With 2 PSU's and 10 miners the complete system was running 90Watt @ 850Mhz (scrypt without fans).
I swapped the two PSU's for a platinum rated 450Watt PSU. Now the complete system is running 70Watt @ 850Mhz (scrypt without fans).