Most if not all broker dealer employees have to pre clear every trade they make with compliance. They make active trading for employees next to impossible. for example: http://www.investmentnews.com/article/20100423/FREE/100429937
I've often wondered if brokerages do this. I've heard the stories about brokerages trading against their clients, and I think someone once posted a story about a futuers broker who woudl flag accounts that had fallen 90% and they brokerage would take the opposite position of trades in those accounts since they were statistically likely to blow their accounts soon.
I wouldn't worry too much about the IB c.s. rep copying your trades in his piker account over his iphone. The only issue at all here is somebody with the ability to frontrun knowing your strategies before you even enter your orders and doing so with size ... or size gunning for your stops, which will kill you anyway if you place them poorly and leave them sitting on the book.
Buffett does not have stops. one stock he owned at price something like 80, went down to 2, then went up to 120.
That would actually be the last thing he'd want - every prime brokerage whom I am aware of has a prop trading desk... although most IBs are supposed to be segregating those desks out of the firms entirely. And yes, your futures orders do get routed through a credit check as they wind their way through the order server. Suggestion: why don't you take your profit with the Dec contract to make it appear like a calendar spread ? You could then offset the legs with the exchange-supported spread.
This gunning for your stops thing is a bunch of BS imo. Think of how many contracts someone would have to trade to push the market into a stop. Now think how big the size of that stop probably is. Why would anyone trade 100s or 1000s of lots to trigger a 1,2,3 etc lot stop? Is there anyone out there who posts a 1000-lot hard stop? Doubtful. Stops get run simply because they accumulate in specific, obvious areas and markets punish the obvious.