True, Jumbo (Non-Agency/Non-Conforming) remains in the high 4's. In many cases you can use a Jumbo loan down to $647,300 but acceptable ratios are tight, cash reserves are significantly different and a host of other hurdles. Some banks won't lend Non-Agency on rentals or to first time home buyers. The rates are attractive, but the rules can be very difficult. Be sure to find out what can be done before focusing on what the rate may be.
On the plus side, let's look at BAC jumbo rates for today. I'm seeing 4.875 30 year fixed for a $1.5m purchase with 20% down. The APR is 4.972 because the website shows a .876 cost to get the rate. That said, it's not the rate you will get. Why? BAC uses a 740 FICO online. Yours is 800. You bank at BAC, and with a high enough balance, your going to get a .25 in fee benefit. Because you have funds to transfer, you could be eligible for a .125 rate reduction. (Most banks have near equal rate/fee improvement options - be sure to check first). The net net of this all is probably a rate of 4.625 for -0- points, perhaps lower.
Best advice I can give would be this: Don't rely on them intarwebs to price compare a loan. Rate data is highly influenced by relationship factors that cannot be overlaid on-line to get an accurate idea of what the terms will end up being. Work with 2-3 banks. Have all of them run your credit (no, it will not impact your score..... that's an urban myth) so that competition will also sharpen the numbers. Finally, commit to one group AFTER YOU ARE UNDER CONTRACT - because any rate quoted prior to being under contract is akin to being the financial equivalent of tech vaporware. With real estate sales slowing and mortgage lenders wondering why the phones aren't ringing, there is currently an explosion of "Oh, my rate is this...." only to be "Oh, my rate is now this because the property is X, or the Fed just moved rates, or your score changed".... In many ways this is why there has been an uptick of resale contract cancellations due to "buyer couldn't perform...."
Best wishes to readers in getting a good deal delivered, not just "quoted", and that the home you have been looking for is finally priced well.