Out of all the issues (1, 2) that Questrade has, cash management is not one of them. I have made several cash withdrawals through the course of late 2010 and 2011 as I have exited my debenture positions and they have been deposited via EFT to my bank account in a timely fashion.
I have been scouring the internet and have been reading nothing but trouble stories from people as they have done significant back-office migration since early February. It generally does not inspire confidence, which is why I entrust most of my idle cash balances to Ally (up to the CDIC limit!) and Interactive Brokers.
As long as you keep your transactions simple with Questrade, you should have no problem with them. If there is anything out of the ordinary or anything that could possibly warrant human interaction, then your mileage will vary – greatly.