FWIW, I started using NAB's iSaver account and closed our ING Direct accounts a while back for our personal banking, not so much because the rate was better (6.3% for NAB vs 6.15% for ING) or because I trusted the NAB any more than I would trust ING ... but because I could access the funds in the NAB iSaver account instantly if I needed them.
It's not that big a deal, but I hate waiting a day each time I want to make a transaction ... I have once or twice done a series of transactions as follows:
1. Say I want to make an expense claim (let's say, $3,000) against my company to reimburse me for business expenses I've paid personally (eg on my personal credit card)
2. Company account doesn't have enough money in it because it loaned it all to my trust as a short term loan (to be paid back before the EoFY). Company looks to the trust to pay back some of the loan now to meet cashflow requirements.
3. Trust bank account doesn't have enough money in it to pay back part of the loan immediately because it is all invested (and more specifically because I don't want to drop my trust bank balance below my usual threshold). This is the only problem with managed funds - short term cashflow can be an issue if distributions are infrequent!
4. Trust looks to borrow some more money from me to cover it's short term cashflow requirements (interest free loan).
5. I don't have enough money in my personal bank account to loan any more to the trust at the moment, because it is all in the savings account.
6. Transfer $5,000 from the NAB iSaver account to my personal bank account
7. Transfer $5,000 from my personal bank account to my trust bank account as a loan (adjust personal Quicken records and trust Quickbooks records to reflect increased loan balance)
8. Transfer $5,000 from trust bank account to company bank account to pay back part of that loan (adjust trust and company Quickbooks records to reflect the decreased loan balance)
9. Transfer $3,000 from company bank account to personal bank account as expense reimbursement, leaving $2,000 in there for other operating expenses. Adjust personal Quicken and company Quickbooks records to show expense claim paid
10. Transfer $3,000 from personal account back into iSaver account
Now imagine doing this if I had to wait a day between transactions

... now it only takes couple of minutes to do it all!
Not that I do this regularly - usually only towards the end of financial year when I'm making sure all expense claims are paid and only if current cashflow situation dictates that I must.
Naturally accurate record keeping is important if you are going to juggle money like this!