Mine is rated for 100Mbps and when I pop a computer on it and do a
speed test I am getting the rated 100Mbps, so unless you are throwing 8-10 cameras on one PLA you would be fine.
I tested it once on different circuits and thru GFCI and with multiple cams and a computer attached and it never hiccuped, but that wasn't an extended test.
I don't think multiple PLA would be an issue as it is simply a digital signal going thru copper line, no different than cable company servicing thousands on a copper line.
The only way to know for sure is to buy one and test it. Every house is different. For example, some haven't been able to get it to work if the units were on different sides of the electric panel, while others have had it work.