Well the thing that makes the auto-setup so great is the room-eq. Hours with an SPL meter can't get the results that these auto-eq systems can even if the receiver has the proper parametric-eq (which most don't). The 43TX offers an intermediate step with manual MCACC but it really only lets you...
3803 BStock for $530 is a heck of a deal. There are tons of 3803 users and it's proven as a very solid receiver. I'm really hoping they get some 2805s or 985s in around the $500 mark.
We've talked about this before, but if you were planning on using the external amp you currently have or plan on adding a more powerful one in the future I would go with the 985S for its processing and room-eq. If not, I would go with the 3803 for its stronger amp section. What kind of price...