Im new to prop, so can't add much to the pros/cons discussion.
However, this comment I can say something about:
"...would require giving up a day job where as someone can gain much more experience and market knowledge working for a brokerage house...this could be done while trading on the side. much lower risk solution."
IF you're referring to a job as a Registered Rep (i.e. stockbroker), you will gain virtually NO market experience. If you work in the firm's trading department, maybe, but only if you're assisting the firm's traders with executing orders, and even then you're executing mostly market and limit orders, NOT trying to trade for profit.
As a Registered Rep, your job will be to hammer the phone all day and SELL. They catch you spending lots of time watching the screen and trying to trade or even papertrade, and your sales manager is going to be all over you because you aren't selling. When I was a broker, we were supposed to try for a minimum of 150 phone calls a day. They kept track of people's call logs, and were on you if it dropped by much.
Finally, when you sell, it'll be the stock's "story," (which you get at numerous dog-and-pony-show breakfast meetings put on by various companies that brokers are required to attend) meaning the fundamentals (they've got this great new widget, they're projected to grow X% in the next year, our research dept. has put out a stong buy recommendation, etc, etc) NOT because of market action, TA, or some fancy trading strategy.