Use discount broker or Listing agent's colleague when buying?

[Nate Si]

Is it better to use a buyer's real estate agent recommended by the listing agent, or use a discount broker and use the commission rebate to bid higher? 

I’m assuming that the seller really only cares about getting the highest price, but the listing agent probably prefers to deal with a buyers agent she knows and likes and someone at her firm so her firm keeps both sides of the deal for commission.

Would using a buyer’s agent recommended by the listing agent, who works at the same brokerage as the listing agent, give me an advantage in a competitive bidding process because the listing agent might tip my agent off about how high I need to bid to beat the other offers?

Or would it be better to just use a discount broker and be able to bid a bit higher since the discount broker will rebate 1.5% or 2% of their 2.5% commission split to me?