I've used them for some years and find them great.
You won't do better than $26 for trades up to $50,000 (NOT $500,000)
and larger trades are no more than others. In fact $45 per $50,000.
I have made larger trades but split them into under $50k bites. That way you are only paying $26 per $50,000 instead of $45 or $55 with others.
Disadvantages? Yes, there is no interest paid on cash balances.
Answer! Leave smaller amounts there and BPay extra funds when you know you are going to trade with larger amounts.
Hope this helps.
PS: my 2 sons also use them on my recommendation AND
I am only a client, have no interest in them and don't work for them.