I don't anticipate having any problems with Lycamobile even as my primary phone. The only problem I've had so far has been with their website when I tried to add money to my account for the first time. I ended up going through a dealer -- from now on I'll just do that -- maybe I can even get a small discount sometimes.
Not having a minimum monthly charge on each line is going to affect the way I use my phone. I'll probably start service back up again on an older phone and just use it when I'm doing things that might be risky with an expensive phone (camping, going to a beach, working in wet areas, whatever). It's a bit of a pain to move sim cards back and forth and there's no need when I can put $5 on a sim and it'll just stay there until I've used it all.