I would say that a suburban or urban permie life is just a different permie life.
I have had a food forest for almost 20 years and eat food from my standard suburban lot every day.
I switched to a less demanding, lower paying job so I could ride my bike to work and spend more time in the garden, playing music and doing things I like, such as skateboarding with my dog.
I don't aspire to grow 100% of my food, but I have great control of many parts of my food supply.
I can ride my bike to several different kinds of Asian, organic, and specialty grocery stores such as Trader Joe's. I ride my bike to the library every week and read many books for free.
It's easy to meet up with other kaykers, baseball players and hang glider pilots.
It's easy to meet people to listen to or play music.
I can go to presentations on sustainable living and also make presentations on them, such as the Home ORchard Society in town.
There are as many advantages to suburban permaculture as there are to rural, but you need to pick the one that fits you best.