re: Brokerage Account as Part of Emergency Account

As long as the money is relatively "safe", it really doesn't matter. Instant transfers are a huge plus to this arrangement, but not really necessary IMO.

Only thing to possibly be careful of is if you make frequent trades, your brokerage may put restrictions on your account. I use Sharebuilder for some investments, tried to make some plays around election time, and got my account partially frozen for some time.